GIFT  or  c.     .*   4- 

Astr-onoialcal   Society 


of  the   Pacific 


AN  INVESTIGATION 


OF  THE 


ROTATION  PERIOD  OF  THE  SUN 


BY   SPECTROSCOPIC   METHODS 


BY 


WALTER    S.    ADAMS 


ASSISTED   BY  JENNIE   B.    LASBY 


L?  8R  ARY 

Or  TVJS 

ASTRONOMICAL  SOCIETY 
OF  THE  PACIFIC 


WASHINGTON,    D.  C. 

PUBLISHED  BY  THE  CARNEGIE  INSTITUTION  OF  WASHINGTON 

191 1 


At^w';".-5  °st  J«°-°ccc'' 


CARNEGIE   INSTITUTION    OF   WASHINGTON 
PUBLICATION  No.  138 


PAPERS  OF  THE  MOUNT  WILSON  SOLAR  OBSERVATORY,  VOL.  I,  PART  I 
UEOKOE  E.  HALE,  Director 

AblRONOMY  DIPT. 


Xortuootj 

J.  8.  Gushing  Co.  — Berwick  &  Smith  Co. 
Norwood,  Mass.,  U.  8.  A. 


TABLE    OF   CONTENTS. 


PAGE 

INTRODUCTION I 

OBSERVATIONS   AND   METHODS   OF   REDUCTION. 

1.  OBSERVATIONS  OK  1906-1907 3 

2.  RECORD  OF  OBSERVATIONS,  1906-1907 6 

3.  METHODS  OF  MEASUREMENT  AND  REDUCTION u 

4.  SOURCES  OF  ERROR 13 

5.  RESULTS  FOR  THE  INDIVIDUAL  PLATES,  1906-1907 15 

6.  OBSERVATIONS  OF  1908 59 

7.  RECORD  OF  OBSERVATIONS,  1908 62 

8.  RESULTS  FOR  THE  INDIVIDUAL  PLATES,  1908 66 

9.  SPECIAL  OBSERVATIONS  ON  THE  a  LINE  OF  HYDROGEN 103 

10.   SPECIAL  OBSERVATIONS  ON  X  4227  OF  CALCIUM 107 

DISCUSSION  OF  THE  RESULTS. 

n.   SYSTEMATIC  DEVIATIONS  OF  VELOCITY  OF  ROTATION  DERIVED  FROM  VARIOUS  LINES  OF  THE  REVERSING   LAYER  109 

12.  INCREASE  OF  DEVIATIONS  IN  HIGHER  LATITUDES ui 

13.  MEAN  RESULTS  FOR  THE  REVERSING  LAYER.  -  VARIABILITY  OF  THE  SOLAR   ROTATION.     COMPARISON  OF  RE- 

SULTS WITH  THOSE  OF  OTHER  OBSERVERS 112 

14.  PROBABLE  ERRORS 117 

15.  COMPARISON  OF  RESULTS  FOR  SUN-SPOTS,  FACUIJE,  FLOCCULI,  REVERSING  LAYER,  THE  a  LINE  OF  HYDROGEN 

AND  X  4227  OF  CALCIUM 118 

16.  A  CASE  OF  LARGE  PROPER  MOTION  IN  THE  REVERSING  LAYER 122 

17.  DETERMINATION  OF  THE  SOLAR  ROTATION  WITH  THE  a  LINE  OF  HYDROGEN 126 

18.  DETERMINATION  OF  THE  SOLAR  ROTATION  WITH  X  4227  OF  CALCIUM 127 

19.  COMPARISON  OF  RESULTS  FROM  ALL  THE  LINES  INVESTIGATED 129 

20.  GENERAL  SUMMARY 130 

BIBLIOGRAPHICAL  REFERENCES 132 

iii 


INTRODUCTION. 


ONE  of  the  earliest  of  the  applications  of  the  Doppler-Fizeau  principle  in  astrophysics  was  to  the  prob- 
lem of  the  rotation  of  the  sun.  The  detection  of  the  minute  displacements  of  the  spectrum  lines  at  the 
sun's  limb  by  Vogel  in  1871  (>)*  not  only  furnished  an  invaluable  proof  of  the  validity  of  the  principle, 
but  also  indicated  the  possibility  of  obtaining,  with  the  aid  of  more  powerful  apparatus,  a  measure  of  the 
rate  of  rotation  by  an  independent  method  free  from  many  of  the  difficulties  possessed  by  such  methods 
as  depend  upon  direct  observations  of  the  solar  surface.  The  invention  of  the  diffraction  grating  made 
it  possible  to  apply  to  the  study  of  the  solar  spectrum  spectroscopes  of  much  greater  power  than  any 
previously  available,  and  with  its  aid  Young  in  1876  (2)  was  able  to  measure  the  displacements  of  the 
spectrum  lines  at  the  sun's  equator  with  a  considerable  degree  of  accuracy,  and  to  show  that  the  results  so 
obtained  were  in  satisfactory  agreement  with  those  derived  from  observations  of  the  sun-spots.  Shortly 
after,  Langley  (3)  and  Cornu  (4)  made  an  interesting  application  of  the  principle  by  showing  how  lines 
due  to  the  earth's  atmosphere  may  at  once  be  distinguished  from  those  of  solar  origin  by  their  freedom  from 
displacement  when  the  spectra  of  the  opposite  edges  of  the  sun  are  observed  simultaneously. 

In  1888  Duner  began  at  Upsala  his  celebrated  investigation  of  the  rotation  of  the  sun  (s).  This  work, 
continued  throughout  1889  and  1890  and  repeated  in  the  years  1901  to  1903,  is  without  doubt  the  standard 
of  reference  among  those  who  have  since  undertaken  the  study  of  this  problem.  Duner  in  this  investiga- 
tion made  use  of  the  suggestion  by  Langley  already  mentioned,  and  by  employing  atmospheric  lines  as  his 
standards  of  reference  was  enabled  to  make  all  of  his  measures  differential,  and  so  to  attain  an  extraor- 
dinarily high  degree  of  precision.  His  determinations  are  grouped  about  points  separated  by  intervals 
of  15°  between  the  solar  equator  and  75°  of  heliographic  latitude,  a  point  far  beyond  the  limit  reached  in 
sun-spot  observations.  With  the  aid  of  these  results  he  was  able  to  discuss  exhaustively  the  validity  of  the 
various  formulae  connecting  the  rotation  period  with  the  latitude  proposed  by  Carrington,  Faye,  and 
Spoerer  as  the  result  of  their  observations  of  sun-spots  between  the  equator  and  45°  of  latitude.  From 
this  discussion  he  concluded  that  Faye's  formula  most  closely  represented  his  independent  observations 
in  the  higher  latitudes.  Many  references  will  be  made  to  this  memoir  of  Duner  in  the  following  pages. 

Following  Duner's  earlier  work  some  photographic  observations  were  made  by  Jewell  at  Baltimore  (6), 
but  no  details  of  the  results  obtained  by  him  have  been  published.  In  1887  Crew  (?)  also  took  up  the  prob- 
lem and  obtained  a  series  of  values  differing  widely  from  those  of  Duner.  It  seems  probable  that  some 
source  of  systematic  error  was  present  in  these  observations,  a  possible  cause,  as  Crew  himself  suggested, 
being  that  arising  from  displacements  of  the  slit  due  to  heating  by  the  sun's  image. 

The  most  recent  investigation  was  that  made  by  Halm  at  Edinburgh  (8)  during  the  years  1903  to  1906, 
and  led  to  results  of  the  highest  accuracy  and  importance.  Like  Duner,  Halm  made  use  of  the  differential 
method,  and  since  the  lines  employed  by  him  are  the  same  as  those  of  Duner,  the  two  series  of  results  are 
strictly  comparable.  In  two  essential  features  the  instruments  used  by  Halm  differ  from  those  of  most 
previous  investigators.  The  first  was  in  the  use  of  a  heliometer  to  form  the  solar  image,  it  being  possible 
by  movement  of  the  divided  object-glass  to  pass  rapidly  from  one  extremity  of  the  solar  diameter  to  the 
other.  The  second  was  in  the  employment  of  a  fixed  horizontal  spectroscope  in  place  of  an  instrument 
attached  to  an  equatorial  telescope  and  moving  with  it.  The  advantages  of  such  a  type  of  spectroscope 
can  hardly  be  questioned,  and  it  was  probably  mainly  due  to  this  cause  that  Halm's  observations  showed 

*  Numbers  in  parenthesis  indicate  references  to  literature  on  p.  133. 


INTRODUCTION. 


%  c'  c'£  £'•»• '     '  ^"c      ' 

such  a  high  degree  of  internal  agreement,  the  probable  errors  being  only  about  one-half  of  those  of  Duner. 
It  was  as  a  result  of  these  observations  that  Halm  concluded  a  variable  period  of  rotation  for  the  sun,  his 
determinations  for  separate  years  showing  large  systematic  deviations  from  each  other.  In  a  final  paper 
on  the  subject  (9)  he  also  discussed  the  later  observations  of  Duner  and  arrived  at  the  conclusion  that  these, 
like  his  own,  gave  evidence  of  a  periodic  variation  in  the  sun's  rate  of  rotation.  The  importance  of  the 
question  thus  raised  can  hardly  be  overestimated,  and  it  will  perhaps  be  the  main  consideration  in  future 
investigations  of  this  problem. 

All  of  the  preceding  determinations  of  the  rotation  period  of  the  sun,  with  the  exception  of  that  of 
Jewell,  have  been  based  on  visual  observations.  While  it  is  probable  that  the  photographic  method  does 
not  possess  tor  such  an  investigation  the  overwhelming  advantages  which  it  has  in  the  case  of  faint  and 
difficult  spectra,  it  has  certain  points  of  superiority  which  render  an  independent  determination  by  its  aid 
of  the  greatest  value.  Two  of  these  are  especially  important.  The  visual  determinations  have  been 
based  upon  a  very  limited  number  of  lines  in  the  less  refrangible  part  of  the  spectrum.  With  the  photo- 
graphic method  it  is  possible  to  employ  a  much  larger  number  of  lines  and  to  utilize  the  more  refrangible 
part  of  the  spectrum  where  the  lines  are  more  numerous  and  the  variety  of  elements  which  can  be 
employed  correspondingly  greater.  These  facts  were  fully  realized  at  the  time  of  the  establishment  of  the 
Mount  Wilson  Solar  Observatory,  and  plans  were  made  for  taking  up  a  photographic  investigation  of  the 
rotation  period  of  the  sun  as  soon  as  suitable  instrumental  equipment  was  ready.  With  the  completion 
of  the  Snow  telescope,  and  the  powerful  i8-foot  spectrograph  used  in  conjunction  with  it,  a  combination 
of  apparatus  admirably  adapted  for  the  work  was  available,  and  accordingly  in  the  spring  of  1906  the  first 
observations  were  begun.  These  were  continued  until  June,  1907,  after  which  all  observational  work  on 
the  rotation  of  the  sun  was  transferred  to  the  tower  telescope. 

Since  the  investigation  was  commenced  five  series  of  observations  have  been  made  and  are  discussed 
in  the  pages  which  follow.  Two  of  these  deal  with  lines  selected  from  the  spectrum  of  the  general  reversing 
layer,  two  with  the  a  line  of  hydrogen,  and  the  fifth  with  X  4227  of  calcium.  The  lines  of  hydrogen  and 
calcium  give  results  differing  widely  from  those  obtained  for  the  reversing  layer,  and  so,  of  course,  should 
be  treated  individually.  Moreover,  since  the  two  series  of  determinations  for  the  reversing  layer  are 
separated  by  a  considerable  interval  of  time,  and  the  apparatus  employed  in  the  second  series  was  entirely 
different  from  that  in  the  first,  it  seems  desirable  to  treat  them  separately  in  the  present  discussion.  Brief 
accounts  of  the  main  results  of  these  two  series  of  observations  have  already  been  published,  the  first  in 
1907  (10)  and  the  second  in  1909  (n).  A  detailed  account  of  the  observations  and  reductions  follows  in 
Sections  i-io.  The  discussion  and  comparison  of  the  results  will  be  considered  in  Sections  1 1-20. 


OBSERVATIONS  AND  METHODS  OF  REDUCTION. 

i.  OBSERVATIONS  OF  1906-1907. 

THE  Snow  telescope  consists  of  a  ccelostat  mirror  of  30  inches  (76.2  cm)  diameter  mounted  equatorially, 
which  throws  a  beam  of  light  upon  a  second  plane  mirror  24  inches  (61.0  cm)  in  diameter  mounted  south  of 
it.  From  this  in  turn  the  light  passes  to  a  concave  mirror  of  24  inches  aperture  and  60  feet  (18.3  m)  focal 
length  placed  at  the  north  end  of  the  telescope  house.  All  of  the  mirrors  are  mounted  upon  masonry  piers 
and  are  supplied  with  slow  motions,  so  that  the  illumination  of  the  concave  mirror  may  be  controlled  from 
the  ccelostat  and  the  position  of  the  image  varied  according  to  the  instrument  with  which  it  is  to  be  used. 
The  direction  of  the  beam  from  the  second  plane  mirror  to  the  concave  mirror  is  not  horizontal  but  is 
inclined  at  an  angle  of  5°,  owing  to  the  nature  of  the  ground  on  which  the  building  is  placed.  For  a  similar 
reason  the  track  upon  which  the  second  mirror  mounting  moves  does  not  point  north  and  south  but  at  an 
angle  of  15°  to  this  direction.  The  ccelostat  mirror  may  be  moved  east  and  west  upon  a  track  and  the 
second  plane  mirror  north  and  south  (more  accurately  northeast  and  southwest)  in  order  to  provide  for  the 
variation  in  the  sun's  declination.  The  concave  mirror  can  be  moved  along  the  direction  of  the  optical  axis  to 
allow  for  focusing  of  the  solar  image,  and  by  simple  rotation  of  the  mirror  the  image  may  be  thrown  upon  any 
instrument  desired.  The  image  formed  by  the  concave  mirror  has  a  mean  diameter  of  6.7  inches  (17.0  cm). 

The  1 8-foot  (5.5  m)  spectrograph  used  in  this  investigation  and  for  many  other  spectrum  studies  as  well, 
in  particular  that  of  the  spectra  of  sun-spots,  is  placed  about  18  inches  (45.7  cm)  to  one  side  of  the  optical 
axis  and  about  12  inches  (30.5  cm)  above  it,  its  tube  lying  directly  above  the  5-foot  spectroheliograph.  It 
is  of  the  Littrow,  or  auto-collimating,  type,  with  a  lens  4  inches  (10.2  cm)  in  diameter  used  with  a  plane 
grating  of  the  same  aperture.  Both  lens  and  grating  are  supported  on  a  cast-iron  base.  The  lens  is  focused 
by  a  screw  and  moves  in  ways  parallel  to  the  optical  axis,  and  may  be  clamped  in  any  desired  position. 
The  grating  is  mounted  in  the  face  of  a  metal  box  which  rests  upon  a  rotating  table,  its  position  being 
defined  by  four  screws  which  touch  its  surface  lightly.  The  original  purpose  of  the  metal  box  was  to  provide 
for  temperature  control,  if  needed,  but  in  the  present  investigation  the  exposures  have  been  so  short  as  to 
render  this  unnecessary.  Reflections  from  the  surface  of  the  lens  are  prevented  from  reaching  the  plate  by 
a  narrow  bar  placed  across  the  lens,  and  in  addition  a  system  of  diaphragms  is  provided  along  the  tube  of 
the  spectrograph.  This  tube  is  of  wood  covered  with  sheet  iron  and  its  central  section  immediately  over  the 
spectroheliograph  can  be  rotated  out  of  place  in  order  to  give  free  access  to  the  prism  box  of  the  latter 
instrument. 

The  slit  and  plate-holder  are  carried  by  a  single  large  casting,  the  base  of  which  rests  on  a  masonry  pier. 
The  distance  between  the  center  of  the  slit  and  the  center  of  the  plate-holder  opening  is  about  3  inches  (7.6 
cm),  an  amount  too  small  to  introduce  any  appreciable  astigmatism  into  the  spectrum  lines.  The  plate- 
holder  may  be  moved  up  and  down  by  a  rack-and-pinion  in  order  to  provide  for  taking  several  exposures  on 
the  same  relate.  In  front  of  the  spectrograph  and  about  6  inches  (15.2  cm)  below  the  slit  is  a  large  cast-iron 
bracket  which  serves  to  support  the  various  auxiliary  attachments  used  in  conjunction  with  the  spectrograph. 

The  marked  advantages  to  be  derived  from  photographing  the  opposite  edges  of  the  sun  simultaneously, 
and  so  doubling  the  displacements  to  be  observed,  led  to  the  employment  of  a  modified  form  of  the  device 
first  suggested  by  Langley.  A  brass  casting  with  a  circular  opening  about  7  inches  (17.8  cm)  in  diameter 
carries  two  brass  arms,  each  of  which  forms  a  radius  of  this  opening  and  rotates  about  its  center.  On  the 
outer  end  of  each  arm  is  mounted  a  small  diagonal  prism,  its  mean  distance  from  the  center  of  rotation 

3 


4       AN  INVESTIGATION  OF  THE  ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC   METHODS. 

corresponding  to  the  mean  radius  of  the  sun's  image.  These  prisms  are  capable  of  adjustment  toward  and 
away  from  the  center  in  order  to  allow  for  variations  in  the  diameter  of  the  sun.  At  the  inner  ends  of  the 
brass  arms  and  immediately  in  front  of  the  slit  are  two  other  diagonal  prisms  which  receive  the  beams  of 
light  from  the  first  pair.  These  prisms  taper  at  the  end  to  a  width  of  0.5  mm,  and  are  mounted  with  their 
edges  about  0.25  mm  apart.  The  latter  distance,  accordingly,  represents  the  separation  on  the  photo- 
graphs of  the  spectra  of  the  two  opposite  edges  of  the  sun.  At  the  outer  ends  of  the  arms  are  pointers  by 
means  of  which  readings  are  made  upon  a  silvered  circle  concentric  with  the  opening  in  the  brass  casting  and 
graduated  to  half  degrees.  The  whole  apparatus  is  mounted  upon  the  cast-iron  bracket  already  referred  to, 
and  its  position  with  reference  to  the  slit  is  accurately  defined  by  two  taper  pins  which  enter  the  bracket. 

The  grating  which  has  been  used  throughout  this  investigation  is  one  of  the  earlier  Rowland  gratings, 
with  ruled  surface  3.25  by  1.75  inches  (8.3x4.4  cm),  and  has  14,438  lines  to  the  inch  (570  lines  to  the 
millimeter).  The  spectra  in  the  second,  third,  and  fourth  orders  on  one  side  of  the  normal  are  exception- 
ally bright  and  the  definition  is  excellent,  in  spite  of  the  great  focal  length  of  the  spectrograph.  For  all 
of  the  work  on  the  rotation  of  the  sun  with  this  spectrograph  the  fourth  order  has  been  used,  the  great 
linear  scale  thus  obtained  being  of  the  utmost  value.  In  this  order,  at  X  4200,  i  mm  =  0.71  Angstrom. 

The  importance  of  accurate  adjustment  of  the  spectrograph  in  a  study  of  small  displacements  can  not 
be  too  highly  emphasized.  In  the  present  investigation  the  greatest  care  has  had  to  be  taken  to  guard 
against  unequal  illumination  of  the  collimating  lens  and  grating  surface  by  the  light  from  the  opposite  edges 
of  the  sun.  It  is  evident  that  a  small  change  in  the  position  of  the  diagonal  prisms  near  the  slit  would  affect 
this  illumination  most  seriously.  Accordingly,  before  each  exposure  it  has  been  my  practice  to  occult  the 
images  of  the  two  edges  in  succession  and  to  examine  the  character  of  the  illumination  from  each  edge. 
The  accuracy  of  this  test  has  been  examined  photographically  and  it  has  been  found  to  be  capable  of  giving 
good  results  when  the  slit  is  narrow  and  the  illumination  is  fairly  weak.  In  addition  to  this  a  valuable 
check  upon  the  accuracy  of  the  adjustment  is  furnished  by  the  relative  density  of  the  pair  of  spectra  on  the 
photographic  plates,  and  no  plates  have  been  included  in  the  series  used  for  measurement  in  which  there  is 
any  marked  difference  in  the  intensity  of  the  spectra  of  the  two  edges  of  the  sun.  A  comparison  of  the  ratio 
of  aperture  to  focal  length  in  the  case  of  telescope  and  spectrograph  shows  that  provided  the  adjustment  is 
reasonably  accurate  the  margin  of  safety  for  full  illumination  of  the  grating  is  considerable.  In  the  case  of 
the  telescope  the  ratio  is  i :  30,  while  in  that  of  the  spectrograph  for  the  full  aperture  of  the  collimating 
lens  it  is  i :  54,  or,  for  the  surface  of  the  grating  actually  employed,  about  i :  72. 

A  brief  description  of  the  actual  procedure  followed  in  taking  the  plates  may  be  of  value.  The  auxiliary 
diagonal  prism  apparatus  is  placed  in  position  in  front  of  the  spectrograph  and  the  image  of  the  sun  cen- 
tered upon  it  and  focused  on  the  slit.  The  image  is  then  slightly  displaced  by  rotation  of  the  ccelostat 
mirror,  the  clock  stopped,  and  the  points  of  transit  observed  of  a  spot  or  other  well-defined  object  on' the 
solar  disk  across  the  position  circle.  Usually  several  sets  of  readings  have  been  made  and  a  mean  taken. 
Since  the  orientation  of  the  image  with  this  form  of  coelostat  mounting  depends  upon  the  position  of  the 
second  plane  mirror  on  its  track  as  well  as  upon  that  of  the  ccelostat  carriage,  these  observations  for  a  line 
of  reference  have  been  made  before  each  series  of  plates,  and  in  most  cases  repeated  after  the  series,  espe- 
cially if  the  interval  covered  is  at  all  long.  Occasionally  the  transits  have  been  obtained  by  rotation  of  the 
ccelostat  mirror  by  means  of  its  slow  motion,  and  comparison  with  the  values  secured  when  the  image  is 
allowed  to  drift  shows  that  there  is  little  choice  between  the  two  methods.  The  range  of  several  such 
determinations  usually  amounts  to  about  o?2  or  o?3-  With  the  aid  of  these  observations  the  east-and-west 
reference  line  is  found  and  the  position  of  the  sun's  pole  and  equator  is  then  readily  computed  from  an 
auxiliary  table,  such,  for  example,  as  is  given  in  the  Companion  to  the  Observatory.  As  soon  as  the  position 
of  the  sun's  equator  is  known,  the  diagonal  prisms  are  set  for  the  latitude  desired,  the  illumination  of 
the  grating  is  examined,  and  the  exposure  taken.  The  second  setting  upon  the  position  circle  is  then  made 
and  the  process  repeated.  Usually  six  exposures  have  been  taken  upon  each  plate,  although  the  number 


OBSERVATIONS   OF    1906-1907. 


varies  according  to  the  latitudes  employed.  In  general,  I  have  used  the  same  plan  as  that  adopted  by 
Duner  of  taking  points  15°  apart  between  o°  and  75°  of  latitude,  but  some  intermediate  points  have  also 
been  added,  particularly  in  the  higher  latitudes  when  the  orientation  of  the  image  was  especially  favorable. 
In  selecting  the  region  of  the  spectrum  to  be  employed  several  considerations  have  been  borne  in  mind. 
The  use  of  photographic  plates  and  the  desirability  of  keeping  the  exposure  times  as  short  as  possible  in 
order  to  avoid  heating  of  the  slit  jaws,  as  well  as  changes  of  focus  and  astigmatism  of  the  solar  image  due 
to  changes  in  the  figure  of  the  mirrors  arising  from  prolonged  exposure  to  the  sun's  heat,  naturally  led  to 
the  employment  of  the  more  refrangible  part  of  the  spectrum.  The  fact  that  the  observations  of  Duner  and 
Halm  were  obtained  in  the  less  refrangible  part  also  made  the  use  of  an  independent  region  most  desirable. 
Although  the  displacement  of  the  spectrum  lines  for  a  given  radial  velocity  is  proportional  to  wave-length 
and  consequently  smaller  in  the  violet  part  of  the  spectrum  than  in  the  red,  this  disadvantage  is  fully 
counteracted  by  the  possibility  of  employing  higher  dispersion  and  fine-grained  photographic  plates  to 
procure  greater  linear  scale  and  higher  resolution.  The  plates  finally  used  were  Seed's  "Process"  plates, 
which  give  excellent  contrast  and  are  appreciably  more  rapid  than  lantern-slide  plates  in  the  violet  part  of 
the  spectrum.  A  second  consideration  which  led  to  the  selection  of  a  region  in  the  violet  was  the  neces- 
sity of  obtaining  the  lines  of  a  sufficient  variety  of  elements  within  the  range  of  wave-length  such  as  could 
be  secured  on  a  single  plate.  After  considerable  examination  the  part  of  the  spectrum  between  X  4200  and 
\  4300  was  selected.  The  plates  employed  are  very  sensitive  to  this  region,  and  within  its  limits  are 
found  an  immense  number  of  lines  including  a  part  of  the  G  group,  as  well  as  the  head  of  the  first  violet 
cyanogen  fluting.  The  presence  of  the  so-called  "blue  line"  of  calcium  at  X  4227  has  also  proved  of  great 
value  in  the  later  observations.  The  list  of  lines  finally  adopted  is  given  in  Table  i.  The  wave-lengths, 
intensities,  and  identifications  are  from  Rowland's  table. 

TABLE  i.  —  LINES  OBSERVED  IN  1906-1907. 


X 

ELEMENT. 

INTENSITY. 

BEHAVIOR  AT  LIMB. 

4196.699 

La 

2 

Much  weakened. 

4197-257 

CN 

2 

Slightly  weakened. 

4203.730 

Cr 

2 

Strengthened  and  widened. 

4209.144 

Zr 

i 

Weakened. 

4216.136 

CN 

i 

Weakened. 

4220.509 

Fe 

3 

Slightly  strengthened  and  widened. 

4232.887 

Fe 

2 

Much  strengthened  and  widened. 

4257.815 

Mn 

2 

Slightly  strengthened  and  widened. 

4258-477 

Fe 

2 

Much  strengthened  and  widened. 

4265.418 

Fe 

2 

Slightly  weakened. 

4266.081 

Mn 

2 

Slightly  weakened. 

4268.915 

Fc 

2 

Slightly  weakened. 

4276.836 

-  Zr 

2 

Weakened. 

4284.838 

Ni 

I 

Slightly  weakened. 

4287.566 

Ti 

I 

Slightly  strengthened  and  widened. 

4288.310 

Ti,  Fe 

I 

Widened. 

4290.377 

Ti 

2 

Slightly  weakened.     Enhanced  line  of  Ti. 

4290.542 

Fe 

I 

Slightly  weakened. 

4291.630 

Fe 

2 

Much  strengthened. 

4294.936 

Zr 

2 

Probably  weakened. 

The  reasons  for  the  selection  of  the  lines  in  the  above  list  are  for  the  most  part  self-evident.  The  lines 
of  cyanogen  are  included  because  of  the  low  level  at  which  carbon,  and  presumably  its  compounds,  lie  in  the 
sun's  atmosphere,  if  we  may  judge  from  chromospheric  observations.  The  line  of  lanthanum  was  selected 
because  of  the  high  atomic  weight  of  this  element,  and  the  consequent  presumption  for  a  relatively  low  level, 


6       AN   INVESTIGATION   OF  THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 

and  the  same  reason  holds  in  lesser  degree  for  zirconium.  Iron  is  represented  by  seven  lines  in  the  list,  a 
number  sufficient  to  eliminate  to  a  great  extent  possible  peculiarities  among  individual  lines  when  a  mean 
value  is  taken.  Titanium  is  of  great  interest  because  of  its  relatively  high  level  in  the  chromospheric 
spectrum,  and  a  larger  number  of  lines  would  have  been  desirable  in  its  case.  The  necessity,  however,  for 
selecting  the  lines  best  suited  for  measurement,  and  free  from  close  neighboring  lines,  has  limited  the  num- 
ber to  three.  Of  these  X  4290.377  is  an  enhanced  line,  that  is,  relatively  stronger  in  the  spark  spectrum 
than  in  that  of  the  arc.  The  other  lines  belong  to  elements  having  an  atomic  weight  close  to  that  of  iron. 
The  last  column  in  Table  i  gives  the  behavior  of  the  lines  at  the  limb  of  the  sun  as  compared  with  the 
center.  At  the  time  at  which  the  list  was  selected  these  remarkable  differences  in  intensity  and  appear- 
ance were  not  known  (12).  It  was  noted  on  the  earliest  plates,  however,  that  the  lines  at  the  limb  as  a  rule 
were  decidedly  broader  and  more  diffuse,  as  well  as  in  most  cases  somewhat  weaker,  than  the  lines  of  the 
ordinary  solar  spectrum  in  this  region.  At  first  this  was  thought  to  be  due  to  some  instrumental  cause, 
possibly  the  long  path  traversed  by  the  light  through  the  glass  of  the  diagonal  prisms,  but  the  discovery 
soon  afterward,  by  Mr.  Hale  and  myself,  of  the  essential  differences  in  character  of  the  spectrum  of  the  sun's 
limb  fully  explained  the  difficulty.  In  view  of  this  relative  diffuseness  of  the  lines  in  the  immediate  neigh- 
borhood of  the  edge  of  the  sun,  it  seems  to  me  probable  that  a  slightly  higher  degree  of  accuracy  might  be 
attained  in  future  observations  by  taking  the  light  from  a  point  somewhat  farther  within  the  disk  than 
that  which  is  usually  employed,  and  applying  the  small  corrections  needed  to  reduce  to  the  sun's  edge. 
Observations  have  shown  that  the  spectrum  of  the  limb  reverts  to  the  normal  solar  spectrum  very  rapidly 
as  the  slit  is  moved  away  from  the  sun's  edge,  and  the  gain  in  the  sharpness  of  the  lines  would  probably 
more  than  compensate  for  the  small  difference  in  the  size  of  the  displacements  measured.  An  accurate 
knowledge  of  the  distance  of  the  slit  from  the  limb  would,  of  course,  be  essential. 

2.    RECORD  OF  OBSERVATIONS,  1906-1907. 

The  series  of  plates  employed  in  this  investigation,  numbering  44,  began  in  May,  1906,  and  extended 
to  June,  1907.  Between  July  and  October,  1906,  no  plates  were  taken,  but  with  the  exception  of  this 
interval  the  period  is  fairly  well  covered.  The  plates  used  do  not  include  all  which  were  taken,  but  careful 
selection  was  made  with  special  regard  to  quality  and  the  conditions  under  which  they  were  obtained. 
Halm  has  called  attention  to  the  importance  of  the  transparency  of  the  sky  in  such  observations,  the  effect 
of  a  hazy  sky,  or  light  cloudiness,  being  to  superpose  the  spectrum  of  skylight  upon  the  spectrum  from  the  edge 
of  the  sun,  and  consequently  to  make  the  displacements  measured  systematically  too  small.  This  point 
was  usually  tested  visually  in  the  same  way  as  was  done  by  Halm,  and  a  few  quantitative  determinations 
of  the  effect  were  also  made  from  photographs  obtained  at  a  time  when  the  sky  was  particularly  hazy. 

The  record  of  the  observations  contained  in  Table  2  gives  the  data  for  the  individual  plates.  The 
estimates  of  the  definition  in  the  fourth  column  are  on  a  scale  of  10.  The  column  headed  "Scale  concave 
mirror"  refers  to  the  setting  of  the  concave  mirror  mounting  upon  its  track  and  is  read  upon  an  arbitrary 
scale.  Positive  readings  indicate  a  direction  north  from  zero,  or  a  greater  distance  between  mirror  and  slit. 
The  considerable  variations  in  these  readings  are  due  to  the  change  of  figure  of  the  system  of  mirrors,  par- 
ticularly of  the  ccelostat  mirror,  when  exposed  to  the  sun's  heat.  This  change  is  dependent  upon  a  variety 
of  conditions,  especially  the  state  of  the  silver  surfaces  of  the  mirrors  and  the  temperature  of  the  air  sur- 
rounding them.  The  column  headed  "Observations  for  zero"  gives  the  readings  of  the  points  of  transit 
across  the  position  circle  of  definite  points  on  the  sun's  disk.  The  method  of  observing  these  has  been  ex- 
plained previously.  The  readings  of  the  position  circle  refer  to  the  settings  of  the  pair  of  diagonal  prisms, 
and  it  is  from  these  settings  that  the  latitudes  of  the  observed  points  on  the  sun's  edge  are  calculated.  The 
numbers  following  the  words  "ccelostat"  and  "second  flat"  in  the  column  of  remarks  indicate  the  positions 
of  these  mirrors  on  their  respective  tracks.  The  orientation  of  the  sun's  image  of  course  is  dependent  upon 
these  quantities. 


RECORD   OF    OBSERVATIONS,    1906-1907. 
TABLE  2. — RECORD  OF  OBSERVATIONS,  1906-1007. 


DATE. 

HOUR 
G.  M.T. 

PLATE 

No. 

DEFINITION.! 

EX- 
POSURE 

TIME. 

SLIT 

WIDTH. 

SCALE 

CONCAVE 
MIRROR. 

OBSERVATIONS 

FOR   ZERO. 

EXPOSURE.  1 

READ- 
INGS 
POSITION 

CIRCLE. 

REMARKS. 

1906 

h    m 

sec 

mm 

0                       » 

0 

May  3 

7  3° 

<"  3 

2 

240 

0.025 

+  10 

80.2-299.3 

i 

219.2 

Zero  very  difficult  on  account  of 

80.3-300.0 

2 

234.2 

definition. 

94.7-286.O 

3 

249-2 

95.1-285.0 

4 

264.2 

96.1-284.7 

5 

279.2 

6 

294.2 

May8 

6     o 

01  6 

4 

250 

0.025 

-18 

114.5-267.5 

i 

293.2 

96.1-286.5 

2 

278.2 

II4.5-266.8 

3 

263.2 

95.6-286.5 

4 

248.2 

5 

233.2 

6 

218.2 

May  19 

10  30 

a  8 

5 

125 

0.025 

+252 

IOI.5-28I.O 

i 

302.0 

Ccelostat  200. 

IOI.7-280.5 

2 

297.0 

Second  Flat  600. 

3 

285.7 

Mirrors  resilvered. 

4 

270.7 

Prisms  cleaned. 

5 

255-7 

Bars  interfere  with  windows  at 

6 

242.0 

300°  and  at  240°. 

7 

225.7 

June  12 

6  45 

ia  19 

5 

45 

0.030 

+  200 

100.6-286.0 

i 

210.3 

100.3-286.0 

2 

234-3 

IO2.2-284.2 

3 

249-3 

IO4.O-282.5 

4 

264.3 

103.6-282.7 

5 

279-3 

6 

294-3 

June  12 

7  1S 

w  20 

5 

60 

O.O3O 

+  2OO 

i 

2IQ  ? 

•*'"OW 

2 

•  *y  po 

234.3 

3 

249-3 

4 

264.3 

5 

279-3 

6 

294-3 

June  12 

7  45 

fe>   21 

5 

60 

0.030 

+  3OO 

i 

204.  ^ 

2 

y*t-o 
278.3 

3 

279-3 

4 

264-3 

5 

249-3 

6 

234-3 

7 

219.3 

June  15 

6     o 

u  23 

4 

65 

0.030 

+  I?0 

102.3-283.8 

i 

293.0 

Ccelostat  300. 

103.0-283.2 

2 

278.0 

Second  Flat  800. 

88.5-298.0 

3 

263.0 

4 

248.0 

5 

233-0 

6 

218.0 

June  15 

6  IS 

u>  24 

3 

65 

0.030 

+  1^0 

i 

218.0 

i  *jv 

2 

233.0 

3 

248.0 

4 

263.0 

5 

278.0 

6 

293.0 

June  15 

6  35 

u  25 

3 

65 

O.O3O 

+  1  SO 

i 

20^.0 

o 

1    *ow 

2 

*yo*v 

278.0 

3 

263.0 

4 

248.0 

5 

233.0 

6 

218.0 

June  16 

6  20 

w  26 

4 

65 

0.030 

+90 

102.3-285.3 

i 

294.7 

Ccelostat  400. 

105.7-284.5 

2 

279.7 

Second  Flat  870. 

105.7-284.7 

3 

264.7 

4 

249.7 

5 

234-7 

6 

219.7 

8      AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  2. —  RECORD  OF  OBSERVATIONS,  1906-1907  —  Continued. 


DATE. 

HOUR 
G.M.T. 

PLATE 
No. 

DEFINITION.  1 

EX- 
POSURE 

TIME. 

SLIT 

WIDTH. 

SCALE 

CONCAVE 
MIRROR. 

OBSERVATIONS 

FOR   ZERO. 

EXPOSURE.  1 

READ- 
INGS 
POSITION 

CIRCLE. 

REMARKS. 

1906 

h    m 

sec 

mm 

0                      0 

0 

June  1  6 

7     5 

w  27 

3 

6? 

O.O^O 

+90 

i 

2O4..7 

J 

W*WO 

I    vv 

2 

**yr-  / 

279-7 

3 

264.7 

4 

249.7 

5 

234-7 

6 

219.7 

Oct.  19 

II    IO 

w  30 

2-3 

75 

0.030 

+260 

83.0-293.0 

i 

72.0 

Angles  reckoned  from  B  readings 

82.8-293.3 

2 

87.0 

on  west  side  position  circle. 

82.5-294.0 

3 

IO2.O 

Ccelostat  112. 

4 

II7.0 

Second  Flat  300. 

5 

132.0 

6 

147.0 

Oct.  19 

12    IO 

w  31 

2-3 

90 

0.032 

+266 

i 

I47.O 

W*VJ* 

2 

Jt  /  -v 
132.0 

3 

II7.0 

4 

102.0 

5 

87.0 

6 

72.0 

Nov.  n 

10      0 

W35 

4 

45 

0.032 

-1-400 

83-5-275-0 

i 

I4I.7 

83-3-275-3 

2 

66.7 

Zero  observations  at  6h  om. 

Nov.  ii 

10  15 

0  36 

4 

CO 

O.O3O 

+400 

I 

66.7 

Distance  between  windows  chanced 

o 

.rf.VJV 

2 

\t\ft  i 

81.7 

to  165.1  mm;    between  inside 

3 

96.7 

edges  83.55  mm. 

4 

111.7 

5 

126.7 

6 

141.7 

Nov.  ii 

10  40 

<a  37 

4 

5° 

0.032 

+400 

i 

141.  7 

2 

****•/ 
126.7 

3 

in.  7 

4 

96.7 

S 

81.7 

6 

66.7 

Nov.  ii 

II       0 

w  38 

4 

55 

O.O?2 

+400 

i 

66  7 

^.VJJ* 

2 

81.7 

3 

96.7 

4 

111.7 

5 

126.7 

6 

141.7 

Nov.  ii 

ii  IS 

<"39 

4 

60 

0.032 

+400 

80.2-280.0 

i 

141.7 

Zero  observations  at  nh  30'™. 

79.8-280.3 

2 

126.7 

79.5-280.3 

3 

111.7 

79.3-280.6 

4 

96.7 

S 

81.7 

6 

66.7 

Dec.  18 

5  5° 

<•)  39^ 

5 

60 

0.032 

+  I2O 

i 

124  C 

2 

*  **f  •  o 

109.5 

3 

94-S 

Dec.  18 

6  40 

w  40 

4-5 

7° 

0.028 

+175 

90.2-296.5 

i 

94-S 

Ccelostat  858. 

90.3-296.0 

2 

i°9-S 

Second  Flat  o. 

90.5-296.0 

3 

124-5 

Zero  observations  at  sh  om  and  at 

90.6-295.2 

4 

124-5 

nh  5™. 

5 

109.5 

6 

94-5 

Dec.  18 

6  50 

<•>  41 

5 

7° 

0.025 

+  140 

i 

124.  C 

2 

*  **+•  J 
109.5 

3 

94-S 

4 

94-S 

5 

109.5 

6 

124-5 

RECORD   OF   OBSERVATIONS,    1906-1907. 

TABLE  2. —  RECORD  or  OBSERVATIONS,  1906-1907  —  Continued. 


DATE. 

HOUR 
G.M.T. 

PLATE 

No. 

I'NOIIINIiaQ 

EX- 
POSURE 

TIME. 

SLIT 

WIDTH. 

SCALE 

CONCAVE 
MIRROR. 

OBSERVATIONS 

FOR   ZERO. 

V) 

READ- 
INGS 
POSITION 

CIRCLE. 

REMARKS. 

igo6 

h    m 

sec 

mm 

0                          0 

° 

Dec.  18 

TO     7Q 

w  46 

6e 

O.O3O 

-4-1  co 

I 

I4I.O 

AW     JW 

«•     if.V 

VO 

*"VO'-' 

1    *  o  v 

2 

I26.O 

3 

126.0 

4 

I4I.O 

5 

I4I.O 

6 

126.0 

Dec.  18 

10  50 

w  47 

4 

70 

0.030 

+  150 

78.0-282.5 

i 

126.0 

78.3-282.7 

2 

I4I.O 

102.5-258.5 

3 

I33-S 

102.0-258.5 

4 

II7.O 

5 

II7.0 

6 

133-5 

1907 

Feb.  3 

5  40 

w  50 

3~4 

70 

0.030 

+  22O 

105.6-289.5 

I 

221.  0 

Zero  observations  at  4h  40™. 

98.6-296.5 

2 

230.0 

101.7-293.5 

3 

246.0 

102.8-292.3 

4 

262.0 

S 

277.0 

6 

293.0 

Feb.  15 

5  4° 

<"55 

4 

60 

0.030 

+  160 

101.0-293.3 

4 

266.0 

Zero  observations  at  sh  om. 

95.5-298.5 

5 

282.0 

93.3-300.5 

6 

297.0 

94.0-300.3 

96.5-298.0 

101.5-292.3 

Feb.  15 

6     5 

w  56 

4 

55 

0.030 

+  180 

94-3-  99-5 

I 

218.0 

95.0-  99.2 

2 

234-0 

3 

250.0 

4 

266.0 

S 

282.0 

6 

297.0 

Feb.  28 

7  '5 

w  60 

2—4. 

60 

0.030 

-(-250 

i 

3O2.O 

O      T1 

2 

O 

302.0 

3 

288.0 

4 

280.3 

S 

273-3 

6 

264.5 

7 

257.5 

Feb.  28 

7  4° 

u  61 

3-4 

60 

0.030 

+250 

97.0-297.3 

i 

248.3 

Zero  observations  at  7h  55™. 

82.0-312.3 

2 

242.3 

102.3-291.6 

3 

242.3 

I35-7-259-3 

4 

248-3 

S 

257.5 

6 

264.5 

Feb.  28 

9  15 

w  62 

3 

65 

0.030 

+  250 

70.5-298.5 

i 

302.0 

Zero  observations  at  9h  30"". 

70.7-298.3 

2 

288.0 

91.0-278.5 

3 

280.3 

123.5-246.0 

4 

273.3 

5 

265.5 

6 

257.5 

Feb.  28 

9  45 

lM>    63 

a 

65 

0.030 

+  250 

i 

251.8 

o 

2 

244.8 

3 

260.6 

4 

267.6 

S 

275.2 

6 

288.8 

April  7 

3  20 

u  64 

5 

90 

0.030 

+  180 

96.3-299.0 

3 

235.0 

Zero  observations  at  oh  iom. 

99.5-295.7 

Mirrors  badly  tarnished. 

105.3-289.7 

93.0-302.2 

105.7-289.5 

10    AN   INVESTIGATION    OF   THE   ROTATION   PERIOD   OF   THE   SUN    BY    SPECTROSCOPIC    METHODS. 


TABLE  2. —  RECORD  or  OBSERVATIONS,  1906-1907  —  Continued. 


DATE. 

HOUR 
G  M.T. 

PLATE 

No. 

DEFINITION.  1 

EX- 
POSURE 

TIME. 

SLIT 

WIDTH. 

SCALE 

CONCAVE 
MIRROR. 

OBSERVATIONS 

FOR    ZERO. 

EXPOSURE.  1 

READ- 
INGS 
POSITION 

CIRCLE. 

REMARKS. 

1907 

h   m 

sec 

mm 

0                          0 

« 

April  7 

5  45 

<•>  67 

IOO 

O  O3O 

4-T  CO 

•3 

2  T  r  r 

April  7 

6  45 

«*•    \J  f 

co  68 

? 

IOO 

o.o^o 

i   *  j** 

o 
6 

235.5 

April  7 

7    IO 

w  60 

o 
1 

IOO 

^'"O 
O.O3O 

4-i  CO 

i 

235.5 

April  22 

/ 

8    20 

*_<y 
w  81 

J 

3 

80 

^'"O 

0.028 

I    *•  3 

+360 

91.5-308.7 

i 

248.0 

Zero  observations  at  7h  30'". 

93-5-306.5 

2 

248.0 

96.0-304.0 

3 

242.5 

4 

242.5 

5 

235-0 

6 

235-0 

May  10 

10  15 

"83 

3-4 

80 

0.025 

+355 

105.0-283.5 

i 

227.0 

Zero  observations  at  gh  20"'. 

93-3-295-5 

2 

232.0 

3 

243.0 

Distance  between  inside  edges  of 

4 

243-0 

windows  changed  to  163.8  mm. 

5 

232.0 

6 

227.0 

May  30 

12    5 

w  85 

3-4 

IOO 

O.O22 

+356 

103.0-285.2 

i 

220.7 

Zero  observations  at  1  11'  40™. 

103.2-285.3 

2 

225.7 

3 

236.7 

4 

236.7 

5 

225.7 

6 

22O-7 

May  31 

4  55 

0,86 

4 

IOO 

O.O2O 

+280 

99.3-290.8 

i 

220.0 

Zero  observations  at  4''  2om. 

99.7-290.5 

2 

225.0 

3 

237.0 

4 

256.3 

5 

271.3 

6 

286.3 

June  22 

3  10 

"87 

3-4 

90 

0.030 

+400 

91.7-279.0 

i 

223.5 

Zero  observations  at  gh  55m. 

2 

230.5 

3 

230.5 

4 

244.0 

5 

259-5 

6 

274-5 

June  22 

II    IO 

088 

3-4 

1  20 

O.O3O 

+400 

i 

274.=; 

".**O** 

2 

*  /  t*o 

259.5 

3 

244.0 

4 

230.5 

5 

230.5 

6 

223.5 

June  22 

ii  40 

u  89 

3-4 

120 

0.030 

+400 

78.0-294.5 

i 

223.5 

Zero  observations  at  1  2h  30™. 

78.0-294.5 

2 

230.5 

3 

230.5 

4 

244.0 

5 

259-5 

6 

274-5 

June  23 

5  20 

w  90 

3 

1  20 

0.032 

+  280 

102.7-283.3 

i 

225.0 

Zero  observations  at  4''  45"'. 

103.0-283.3 

2 

236.5 

3 

234.0 

4 

252.2 

5 

267.7 

6 

282.7 

June  23 

5  20 

ft)  91 

3 

1  20 

0.032 

+  280 

i 

282.7 

2 

267.7 

3 

252.2 

4 

236.5 

MEASUREMENT  AND  REDUCTION.  II 

3.  METHODS  OF  MEASUREMENT  AND  REDUCTION. 

The  series  of  photographs  used  in  this  investigation  have  been  measured  upon  two  comparators,  one 
by  Toepfer  of  Potsdam,  with  a  150  mm  screw,  and  the  other  by  Gaertner  of  Chicago,  with  an  80  mm  screw. 
The  Toepfer  instrument  has  been  used  by  Miss  Lasby  of  the  Computing  Division,  and  the  Gaertner  ma- 
chine by  myself.  The  screws  of  both  comparators  have  a  pitch  of  0.5  mm  and  have  been  investigated  for 
periodic  errors  as  well  as  for  errors  of  run,  with  results  which  have  proved  most  satisfactory.  In  the  case 
of  the  Toepfer  instrument,  upon  which  a  majority  of  the  plates  have  been  measured,  the  series  of  determi- 
nations of  a  fixed  distance  ruled  on  a  glass  plate  for  every  alternate  10  revolutions  of  the  screw  between  10 
and  280  indicates  remarkably  small  periodic  errors.  At  a  maximum  these  amount  to  0.3  p  (0.0003  mm), 
which  is  considerably  below  the  limit  of  accuracy  of  measurement  for  spectrum  plates.  The  reading 
head  of  the  Toepfer  comparatoris  divided  into  100  parts,  and  so  can  be  read  directly  to  5  /u,  and  by  esti- 
mation to  0.5  fj..  The  errors  of  run  are  also  small,  but  of  course  do  not  need  to  be  considered  in  small 
differential  measures  of  this  sort. 

An  examination  of  the  screw  of  the  Gaertner  comparator  indicates  periodic  errors  amounting  at  a  maxi- 
mum to  2  fj..  If  this  amount  entered  fully  into  the  value  of  the  displacements  it  would  of  course  be  neces- 
sary to  apply  corrections  for  it.  Since  the  maximum  error,  however,  applies  only  to  a  half-revolution  of  the 
screw,  that  is,  250  p,  while  the  largest  displacements  measured  (at  the  sun's  equator)  are  90  fj,,  it  is  evident 
that  only  about  one-third  of  the  total  value  can  affect  the  measures.  Moreover,  in  reversing  the  plate  for 
the  second  series  of  measures,  care  has  been  taken  to  set  the  plate  in  such  a  way  that  the  opposite  part  of 
the  revolution  of  the  screw  is  employed  to  that  used  in  the  first  series.  The  effect,  accordingly,  is  to 
balance  the  errors  in  the  two  cases,  and  it  seems  altogether  probable  that  the  errors  due  to  the  irregularities 
of  the  screw  with  this  comparator,  as  in  the  case  of  the  larger  instrument,  fall  well  below  the  errors  of 
measurement.  The  reading  head  of  the  Gaertner  comparator  is  divided  into  500  parts,  so  that  settings 
can  be  made  directly  to  i  /j,,  and  estimations  to  o.i  p,  if  desired. 

The  procedure  followed  in  measuring  the  plates  is  as  follows.  After  the  plate  has  been  adjusted  on  the 
comparator  so  that  the  small  interval  separating  the  two  spectra  of  the  opposite  limbs  falls  at  the  center  of 
the  field  of  view,  and  the  plate  has  been  carefully  lined  up  for  parallelism  to  the  direction  of  motion  of  the 
screw,  four  settings  are  made  on  each  line  in  the  two  spectra.  The  difference  between  the  means  of  these 
settings  gives  the  relative  displacements  of  the  lines  between  the  two  limbs,  or  double  the  displacement 
due  to  the  rotation  of  the  sun.  After  the  whole  plate  has  been  measured  throughout  in  this  way  it  is 
reversed  and  a  similar  series  of  settings  made  in  the  second  position.  Since  only  dark  lines  are  involved, 
no  such  systematic  differences  between  the  results  in  the  two  directions  due  to  physiological  causes  are 
found  as  in  the  case  of  spectra  in  which  a  comparison  spectrum  with  bright  lines  is  used,  but  the  additional 
set  of  measures  has  proved  most  useful  in  correcting  peculiarities  in  the  appearance  of  individual  lines,  and 
a  higher  degree  of  accuracy,  of  course,  is  obtained  from  this  doubling  of  the  number  of  settings.  The  means 
of  the  displacements  obtained  from  the  two  series  of  measures  are  then  combined  to  give  the  final  values. 
The  complete  measurement  in  both  directions  of  a  plate  containing  6  latitudes  involves  a  total  of  1920 
settings. 

A  most  important  consideration  in  the  measurement  of  the  plates  is  the  question  of  the  inclination  of  the 
micrometer  wire  in  the  eye-piece  of  the  measuring  instrument.  Unless  this  is  accurately  parallel  to  the 
true  direction  of  the  spectrum  lines,  a  considerable  error  may  be  introduced  into  the  displacements,  since 
reversal  of  the  plate  does  not  affect  the  position  of  the  wire  in  this  regard.  It  is  evident  that  the  correc- 
tion could  be  obtained  by  making  the  second  measurement  through  the  glass,  but  the  practical  objections 
to  this  procedure  are  obvious,  and  it  is  probable  that  small  errors  might  be  introduced  by  refraction  in  the 
glass  plate.  Accordingly,  the  following  method  was  finally  adopted.  A  solar  spectrum  taken  with  a  long 
slit  was  obtained  at  the  center  of  the  sun  with  the  direction  of  the  slit  parallel  to  the  sun's  axis,  a  position 


12       AN   INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


in  which  the  inclination  of  the  lines  evidently  would  not  be  affected  by  the  sun's  rotation.  With  this  plate 
as  a  standard  the  vertical  micrometer  wire  was  carefully  adjusted  until  it  coincided  with  the  lines  of  the 
spectrum  throughout  their  entire  length  and  then  clamped  in  position.  Since  the  lines  of  the  rotation 
spectra  are  very  short  (about  1.5  mm  for  each  pair  of  spectra),  it  is  evident  that  the  accuracy  of  adjustment 
for  these  spectra  must  be  all  that  can  be  desired.  When  any  change  in  the  inclination  of  the  slit  has  been 
made,  or  the  grating  rotated  about  a  vertical  axis,  a  new  standard  plate  has  been  taken  and  the  micrometer 
wire  readjusted.  This  has  been  done  on  but  one  occasion  in  the  present  series  of  observations. 

After  the  linear  displacements  have  been  obtained  in  this  way  the  conversion  into  velocity  is  effected  by 
the  aid  of  Table  3.  The  second  column  gives  the  factor  for  conversion  of  the  displacements  into  Angstrom 
units,  and  the  third  the  value  of  a  displacement  of  one  Angstrom  unit  in  kilometers  for  each  of  the  lines 
measured.  The  last  column  is  the  product  of  the  two  by  the  factor  one-half,  since  double  the  rotational 
velocity  is  actually  measured.  It  is  this  column  which  is  used  in  practice.  The  table  is  for  the  Toepfer 
comparator ;  for  the  Gaertner  instrument  the  quantities  in  the  second  and  fourth  columns  are  twice  as 
large,  since  the  unit  of  measurement  is  the  millimeter  instead  of  the  half-millimeter  as  in  the  case  of  the 
Toepfer  comparator. 

TABLE  3.  —  CONVERSION  or  DISPLACEMENTS  INTO  VELOCITIES.    OBSERVATIONS  OF  1906-1907. 


X 

ONE  ^REVOLUTION 

ONE  ANGSTROM 

ONE-HALF  REVO- 

x 

ONE  ^REVOLUTION 

ONE  ANGSTROM 

ONE-HALF  REVO- 

IN ANGSTROMS. 

IN    KM. 

LUTION  IN  KM. 

IN  ANGSTROMS. 

IN    KM. 

LUTION  IN  KM. 

4196.699 

0-3546 

71-45 

12.67 

4266.081 

0.3508 

70.29 

12.33 

4197-257 

0.3546 

71-44 

12.66 

4268.915 

0.3506 

70.24 

12.32 

4203.730 

0-3543 

71-33 

12.64 

4276.836 

0.3502 

70.11 

12.28 

4209.144 

0-354° 

71.24 

12.61 

4284.836 

0-3497 

69.98 

12.24 

4216.136 

0.3536 

71.12 

12.58 

4287.566 

0-3496 

69.94 

12.22 

4220.509 

0-3534 

71-05 

12.56 

4288.310 

0-3495 

69.92 

12.22 

4232.887 

0.3527 

70.84 

12.50 

4290.377 

0.3494 

69.89 

12.21 

4257-815 

0.3512 

70-43 

12.36 

4290.540 

0-3494 

69.89 

12.21 

4258.477 

0-3512 

70-42 

12.36 

4291.630 

0-3494 

69.87 

12.20 

4265.418 

0.3508 

70.30 

12-33 

4294.936 

0-3491 

69.82 

12.  l8 

The  velocities  obtained  in  this  manner  are  those  observed  directly,  and  in  order  to  convert  them  into 
the  velocities  corresponding  to  the  sidereal  rotation  period  of  the  sun  it  is  necessary  to  apply  three  correc- 
tions. The  first  of  these  is  the  small  correction  for  reduction  to  the  edge  of  the  sun,  since  the  slit  is  always 
set  a  small  distance  inside  the  limb.  This  is  readily  found  by  computation,  since  the  distance  of  the 
diagonal  prisms  whif  h  admit  the  light  is  accurately  known  with  reference  to  the  center  of  the  sun,  and  the 
diameter  of  the  image  for  any  date  can  be  found  by  the  aid  of  an  almanac  when  the  setting  of  the  concave 
image-forming  mirror  is  known.  The  correction  accordingly  will  always  take  the  form  of  multiplication 
by  a  factor  slightly  greater  than  unity.  A  slight  allowance  has  been  made  for  the  difference  in  the  size  of 
the  solar  image  at  the  focus  and  at  the  point  where  the  light  falls  upon  the  diagonal  prisms. 

The  second  correction  is  that  for  the  departure  of  the  sun's  pole  from  its  visible  edge.  In  this  case  the 
correction  consists  of  multiplication  by  the  secant  of  an  auxiliary  angle  which  is  designated  by  ??  in  Duner's 
memoir  (sa),  and  for  the  derivation  of  which  the  necessary  formulae  have  been  given  by  him  in  full.  If  we 

put 

i  =  inclination  of  the  sun's  equator 
O  =  longitude  of  the  sun 

fl  =  longitude  of  the  ascending  node  of  the  sun's  equator 
TT  =  polar  distance  of  the  point  observed 


DISCUSSION   OF   ERRORS.  13 

the  formula  reads 

sin  r,  =  _  sinisin(Q-n) 

SUITT 

In  all  cases  in  which  the  value  of  ~n  is  large  the  values  have  been  worked  out  rigorously.  In  the  lower 
latitudes,  where  the  values  of  n  are  comparatively  small  and  vary  but  slightly,  use  has  been  made  of  the 
convenient  table  given  by  Duner. 

A  third  correction  is  required  to  allow  for  the  earth's  motion  in  its  orbit,  or,  in  other  words,  to  reduce 
the  observed  values  of  the  rotation  period  of  the  sun  to  the  sidereal  rotation  period.  The  formulae  neces- 
sary for  the  derivation  of  this  correction  have  also  been  worked  out  completely  by  Duner  and  are  given 
by  him  in  his  memoir,  together  with  excellent  tables  of  reference.  Frequent  use  has  been  made  of  these 
in  reducing  the  results  given  here.  It  would  of  course  give  the  same  final  values  to  convert  the  observed 
linear  velocities  into  angular  velocities  and  then  apply  the  corrections  necessary  to  allow  for  the  earth's 
motion  directly  from  the  almanac  values,  and  in  some  ways  this  procedure  would  be  preferable.  To 
facilitate  comparisons  with  other  results  it  has  seemed  desirable  to  add  the  corrections  directly  to  the 
linear  velocities.  The  total  value  of  this  correction  varies  from  o  at  the  pole  to  about  0.14  km  at  the 
equator. 

The  computation  of  the  heliographic  latitudes  of  the  points  under  observation  is  made  in  the  following 
way  with  the  aid  of  De  La  Rue's  Tables  for  Determining  the  Angle  of  Position  of  the  Sun's  Axis  :  The  position 
angle  of  the  sun's  axis  in  reference  to  the  north  point,  as  well  as  the  heliographic  latitude  of  the  earth,  is 
found  for  the  date  of  observation,  the  tables  being  constructed  with  the  sun's  longitude  as  an  argument. 
The  position  of  the  north  point  is  found  in  the  way  already  explained  by  transits  of  the  sun's  disk  across 
the  position  circle  of  the  instrument.  Accordingly,  if 

p  =  position  angle  of  point  from  sun's  north  point 
P  =  angle  of  sun's  pole  from  north  point 
D  =  earth's  heliographic  latitude 

the  heliographic  latitude  $  of  the  point  desired  is  found  by  the  formula 

sin  <f>  =  cos  (p  —  P)  cos  D 
The  polar  distance  IT  is,  of  course,  the  complement  of  the  angle  <£. 

4.    SOURCES  OF  ERROR. 

As  in  all  quantitative  investigations  of  the  displacements  of  spectrum  lines,  the  errors  in  the  results 
obtained  in  the  present  study  naturally  fall  under  two  heads.  Under  the  first  are  those  due  to  instrumental 
causes,  leading  to  errors  in  the  values  of  the  displacements  on  the  plates.  Under  the  second  fall  errors 
arising  from  the  measurement  of  the  plates  and  the  reduction  of  the  results  obtained.  There  can  be  little 
doubt  that  of  these  two  the  first  is  by  far  the  more  serious,  since  errors  of  this  sort  are  much  more  liable 
to  be  of  a  systematic  character  than  those  arising  from  either  measurement  or  reduction. 

The  principal  sources  of  error  to  be  considered  under  the  first  head  are  as  follows  : 

(1)  Astigmatism,  changes  of  focus,  and  lack  of  definition  of  the  solar  image. 

(2)  Heating  of  the  slit  jaws  during  exposures. 

(3)  Unequal  illumination  of  the  grating  from  the  opposite  edges  of  the  sun. 

(4)  The  presence  of  the  spectrum  of  skylight,  which  tends  to  reduce  the  values  of  the  displacements 
observed. 

I  have  already  discussed  (3)  and  (4)  in  a  preceding  paragraph  and  described  the  precautions  taken  to 
avoid  the  introduction  of  error  from  them.  It  seems  probable  that  any  difficulty  due  to  the  presence  of  the 
skylight  spectrum  can  hardly  be  appreciable  when  the  plates  used  for  measurement  have  been  selected 


14      AN  INVESTIGATION  OF  THE  ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC   METHODS. 

from  those  taken  on  especially  transparent  days.  Experiments  made  by  Mr.  Hale  and  myself  (13)  have 
indicated  that  on  a  day  of  average  transparency  on  Mount  Wilson  the  brightness  of  the  sky  spectrum 
close  to  the  edge  of  the  sun  is  about  one-fortieth  that  of  the  spectrum  inside  the  limb.  Accordingly,  this 
would  represent  about  the  maximum  effect  in  the  case  of  the  plates  under  consideration,  and  a  contribution 
of  one-fortieth  to  the  intensity  of  the  spectrum  lines  would  probably  be  entirely  inappreciable  both  in  the 
appearance  of  the  plates  and  in  the  measurement.  The  influence  of  inequalities  in  the  illumination  of  the 
grating  can  probably  never  be  absolutely  eliminated,  but  with  the  aid  of  the  precautions  taken  in  securing 
the  exposures  I  feel  confident  that  the  effect  has  been  reduced  to  a  minimum,  and  that  in  an  extended 
series  of  observations  the  residual  effect  can  be  regarded  mainly  as  an  accidental  error  which  will  tend  to 
eliminate  itself  with  a  sufficient  number  of  plates. 

The  question  of  the  heating  of  the  slit  jaws  during  the  exposures  has  been  treated  with  especial  care, 
since  errors  arising  from  this  source  have  been  encountered  by  other  observers.  On  account  of  the  com- 
paratively small  ratio  of  i :  30  between  aperture  and  focal  length  in  the  Snow  telescope,  and  the  relatively 
large  image  employed,  the  amount  of  heat  which  falls  upon  the  slit  is  of  course  much  less  than  in  the  case  of 
relatively  short  focus  telescopes.  Additional  advantages  are  the  silvering  of  the  slit  jaws,  which  helps  to 
reflect  the  heat  that  falls  upon  them,  and  the  fact  that  a  length  of  only  about  3  mm  of  the  slit  is  exposed  to 
the  sun  when  the  plate  is  taken.  In  order  to  obtain  a  definite  test,  however,  I  have  tried  several  exposures 
upon  the  same  part  of  the  sun,  using  a  comparison  spectrum  obtained  with  and  without  the  interposition 
of  a  glass  cell  containing  a  thickness  of  20  mm  of  water.  Such  a  screen  could  hardly  fail  practically  to 
eliminate  heat  effects  on  the  slit.  The  measurement  of  these  plates  has  indicated  no  difference  whatsoever 
between  the  results  obtained  with  and  without  the  screen,  and  the  conclusion  seems  to  be  warranted  that 
any  effect  upon  the  rotation  values  due  to  heating  of  the  slit  jaws  during  the  exposures  must  be  very  small. 

The  first  source  of  error  referred  to  in  the  list,  which  has  to  do  with  the  astigmatism  and  lack  of  definition 
of  the  sun's  image  upon  the  slit  of  the  spectrograph,  is  perhaps  the  most  serious  of  any  encountered  in 
the  investigation.  In  working  with  the  Snow  telescope  we  have  found  that  the  definition  of  the  solar  image 
toward  the  middle  of  the  day  is  much  inferior  to  what  it  is  in  the  early  morning  and  late  afternoon,  and 
that  the  effect  of  prolonged  exposure  of  the  mirrors  to  sunlight  at  this  time  of  day  is  to  introduce  a  consid- 
erable amount  of  astigmatism  due  to  changes  of  figure  of  the  plane  mirrors.  This  shows  itself  in  a  distortion 
of  the  image  and  a  difference  of  focus  between  the  vertical  and  horizontal  diameters.  The  effect  of  this 
upon  determinations  of  rotation  is  to  introduce  into  the  slit  additional  light  from  points  differing  slightly 
in  latitude  from  those  upon  which  the  diagonal  prisms  are  set,  and  also  to  cause  a  slight  difference  for 
different  latitudes  in  the  distance  from  the  sun's  edge  at  which  the  light  is  taken.  The  first  is  probably 
much  the  more  serious.  The  effect  of  changes  of  focus  during  the  exposures  is  also  in  the  direction  of 
bringing  into  the  slit  scattered  light  from  other  latitudes  than  those  upon  which  the  instrument  is  set, 
and  the  same  holds  true  of  most  defects  in  the  character  of  the  sun's  image. 

Since  the  plates  for  the  determination  of  the  rotation  of  the  sun  have  been  taken  for  the  most  part 
toward  the  middle  of  the  day,  the  early  morning  hours  and  the  late  afternoon  being  utilized  for  the  spec- 
troheliograph,  the  effects  discussed  here  must  have  influenced  the  results  obtained  to  a  certain  extent. 
The  selection  of  the  plates  to  be  used  for  measurement,  however,  and  the  rejection  of  those  which  were 
obtained  under  especially  unfavorable  conditions,  must  have  rendered  decidedly  less  the  amount  of  the 
error  from  this  source  which  can  enter  into  the  determinations.  In  taking  the  plates  it  has  been  found 
possible  to  reduce  materially  the  amount  of  astigmatism  and  variation  of  focus  by  keeping  the  mirrors 
cooled  by  a  circulation  of  air  about  them  from  electric  fans,  and  by  shutting  off  the  sunlight  for  short  inter- 
vals between  the  successive  exposures  on  the  plate.  It  is  evident  that  even  in  the  case  of  a  poorly  defined 
image  the  main  effect  of  the  introduction  into  the  slit  of  the  scattered  light  from  points  bordering  on  the 
latitudes  employed  will  be  to  widen  the  lines  without  altering  the  displacements  seriously,  since  in  general 
the  foreign  light  will  come  from  regions  distributed  symmetrically  about  these  points  of  latitude.  In  the 


RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907.  15 

case,  however,  of  a  marked  change  in  the  character  of  the  image  during  the  exposures  on  the  various  lati- 
tudes, systematic  errors  might  be  introduced,  and  such  effects  would  naturally  be  greater  in  the  higher 
latitudes,  where  the  change  of  velocity  with  the  latitude  is  more  rapid  than  it  is  near  the  equator.  It  is 
of  course  impossible  to  say  to  what  extent  these  effects  may  have  entered,  and  I  can  only  emphasize  the 
fact  that  all  the  precautions  which  have  seemed  feasible  have  been  taken  to  keep  the  character  of  the  image 
the  same  during  the  series  of  exposures. 

A  consideration  of  the  second  class  of  errors  which  may  influence  these  results,  those  that  arise  from 
errors  of  measurement  and  reduction,  may  be  passed  over  rapidly.  The  methods  of  measurement  and  the 
screw  errors  affecting  the  instruments  employed  have  already  been  discussed  in  full,  and  it  seems  probable 
that  there  can  be  but  little  systematic  error  due  to  this  source  affecting  the  results.  In  the  reductions, 
moreover,  methods  rigorous  within  the  limits  of  accuracy  required  have  been  followed,  and  consequently 
there  is  little  to  be  feared  from  this  source  except  as  regards  numerical  errors  of  computation.  To  avoid  the 
latter  a  considerable  part  of  the  work  has  been  done  in  duplicate,  especially  that  involving  the  various  cor- 
rections to  the  observed  velocities  and  the  computation  of  the  latitudes.  The  conversion  of  the  measured 
displacements  into  velocities  is  readily  checked  by  comparison  with  a  standard  table. 

In  conclusion  it  should  be  noted  that  small  absolute  errors  may  be  introduced  into  the  results  by 
uncertainty  in  the  values  of  the  constants  of  reduction  employed.  Throughout  the  observations  of 
1906-1907  the  following  values,  by  Carrington,  of  the  inclination  of  the  sun's  equator  /  and  the  longitude 
of  its  ascending  node  ^  have  been  used. 

i  =  fi5'  «=  74°  24'  (1906) 

In  concluding  this  discussion  of  the  sources  of  error  in  the  observations,  reference  should  be  made  to  a 
class  of  phenomena  present  in  the  sun  which  under  certain  conditions  may  very  seriously  affect  the  results 
obtained  for  the  rotation.  These  are  the  disturbances  in  the  solar  atmosphere  which  have  been  discussed 
recently  under  the  term  "  Solar  Vortices  "  (u),  although  their  character  is  as  yet  by  no  means  clear.  The 
influence  of  the  presence  of  such  disturbances  will  be  referred  to  more  fully  in  connection  with  the  considera- 
tion of  the  series  of  observations  of  1908,  and  some  numerical  results  will  be  given  at  that  time.  It  is 
sufficient  to  call  attention  here  to  the  fact  that  these  solar  storms  sometimes  affect  very  large  regions  of  the 
sun's  surface,  and  that  throughout  these  regions  the  velocities  due  to  the  rotation  of  the  sun  may  be  greatly 
modified  by  the  proper  motions  of  the  areas  involved. 

5.    RESULTS  FOR  THE  INDIVIDUAL  PLATES,  1906-1907. 

The  detailed  results  for  the  separate  plates  used  in  this  investigation  are  given  in  Table  4.  The  main 
consideration  borne  in  mind  in  the  construction  of  this  table  has  been  to  give  all  the  data  essential  to  an 
independent  computation  of  the  values  derived  from  the  plates.  With  this  in  view,  at  the  beginning  of  the 
summary  for  each  plate  are  given  the  constants  used  in  the  reduction  of  that  plate,  together  with  the 
necessary  data  for  the  computation  of  the  latitudes  and  the  auxiliary  angles  employed  in  correcting  the 
observed  values.  Although  most  of  the  symbols  have  already  been  defined,  for  the  sake  of  convenience 
it  may  be  well  to  repeat  them  at  this  point. 

O  =  longitude  of  sun. 

fl  =  longitude  ascending  node  of  sun's  equator  =  74?4  for  1906. 

P  -  angle  between  sun's  pole  and  north  point. 

D  =  earth's  heliographic  latitude. 

"f  =  heliographic  polar  distance  of  point  observed  =  90°  —  <f>. 

n  =  angle  made  by  the  plane  passing  through  the  point  observed,  the  sun's  pole,  and  its  center, 
with  the  plane  corresponding  to  the  sun's  visible  edge. 


l6     AN  INVESTIGATION   OF  THE  ROTATION  PERIOD  OF  THE   SUN  BY   SPECTROSCOPIC  METHODS. 

The  diameter  of  the  image  is  found  by  computation  in  the  way  already  described  from  the  almanac 
value  of  the  sun's  angular  semi-diameter  combined  with  the  concave  mirror  setting  of  the  Snow  telescope. 
The  "factor"  referred  to  is  the  semi-diameter  divided  by  one-half  the  distance  between  the  diagonal  prism 
openings  which  admit  the  light  to  the  slit. 

The  results  for  the  individual  lines  of  each  plate  for  the  various  latitudes  are  given  immediately  below 
the  constants  for  the  plate.  The  values  of  A  are  the  mean  total  displacements  expressed  in  half-milli- 
meters. Hence  the  largest  displacements  measured  are  about  0.075  mm-  In  the  case  of  plates  measured 
with  the  Gaertner  comparator  the  values  of  the  displacements  have  been  multiplied  by  two,  in  order  to 
make  all  of  the  quantities  given  homogeneous.  The  meaning  of  the  other  symbols  employed  in  the  tables 
is  as  follows : 

v    =  linear  velocity  corresponding  to  the  sun's  synodic  period  of  rotation. 

ill  —  correction  for  reduction  to  sidereal  period  of  rotation. 

£    =  daily  angular  velocity  corresponding  to  the  sidereal  period  of  rotation. 

It  is  evident  from  the  consideration  of  the  methods  of  reduction  that 

[  Value  one-half  revolution  1 

v  =  A  x  \  .  }  x  Factor  x  sec  rj 

[      of  micrometer  in  km     j 

The  values  of  the  second  quantity  are  obtained  from  the  last  column  of  Table  3.     The  corrections  v\  are 
from  the  tables  of  Duner  (s).     The  value  of  £  is  readily  found  from  v  +  vl  by  means  of  the  formula 

,  v  +  vl 
=  [0.851228]  - 

J  COS$ 

where  N  is  the  number  of  seconds  in  a  mean  solar  day  and  R  is  the  sun's  radius  in  kilometers. 

Some  of  the  values  for  the  individual  plates  given  in  Table  4  differ  to  a  certain  extent  from  those  which 
appeared  in  an  earlier  communication  (10).  This  is  due  mainly  to  the  inclusion  of  a  number  of  measures 
of  plates  by  myself  which  I  have  found  an  opportunity  to  make  in  the  interval  since  the  first  publication. 
As  a  consequence  the  mean  values  obtained  represent  much  more  nearly  the  average  values  for  the  two 
observers,  Miss  Lasby  and  myself,  than  did  the  earlier  results.  The  values  given  here  should  accordingly 
be  more  nearly  free  from  systematic  peculiarities  of  measurement.  There  are  also  a  few  changes  due  to 
revision  of  the  constants  applied  for  correction  of  the  observed  velocities,  particularly  of  the  constant  of 
reduction  to  the  sidereal  period  of  rotation.  The  final  effect  of  all  such  changes  on  the  mean  values,  how- 
ever, is  very  small,  the  largest  difference  in  the  mean  for  any  normal  place  amounting  to  about  0.005  km. 
In  the  table  the  abbreviations  L.  and  A.  refer  to  Miss  Lasby  and  myself,  while  the  two  comparators  used, 
the  Toepfer  and  Gaertner  instruments,  are  designated  by  T.  and  G.  respectively. 


RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


Plate 


TABLE  4.  —  •  RESULTS  FOE  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907. 
3.     1906,  May  3,  7h  30™  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  2.4  mm.    Quality,  good. 


p-P 

7T 

<t> 

17 

seci; 

g 

g 

e 

0 

0 

O 

42.4 

5-2 

6.4 

83.6 

36.9 

1.250 

o-n  - 

-  32-0     . 

20.2 

20.5 

69-5 

II.O 

1.019 

p 

23-9 

35-2 

35-4 

54-6 

6.6 

1.007 

D      - 

-    3-8 

50.2 

50-3 

39-7 

5-o 

1.004 

Diameter 

172.0  mm 

65.2 

65-3 

24-7 

4.2 

1.003 

Factor 

1.028 

80.2 

80.2 

9.8 

3-9 

i.  002 

0=9?8 

<t>  =  24?7 

0  =  39?7 

X 

A 

V 

JI  +  PJ 

E 

A 

V 

t  +  vl 

f 

A 

V 

»+!>! 

£ 

km 

km 

0 

km 

km 

. 

km 

km 

e 

4196.699 

0.145 

1.891 

2.027 

14.61 

0.127 

1-658 

1.787 

13.96 

0.098 

1.282 

1-395 

12.87 

4I97-2S7 

0-145 

1.891 

2.027 

14.61 

0.128 

1.670 

1.799 

14.06 

O.IOO 

1-305 

1.418 

13.08 

4203.730 

0.146 

1.896 

2.032 

14.64 

0.130 

1.692 

1.821 

14-23 

0.100 

1-303 

1.416 

13.06 

4209.144 

0.146 

1.890 

2.026 

14.60 

0.132 

1.714 

-843 

14.40 

O.IO2 

1.327 

1.440 

13.29 

4216.136 

0.146 

1.887 

2.023 

14.58 

0.129 

1.672 

.801 

14.07 

O.IOO 

1.297 

1.410 

13.01 

4220.509 

0-145 

1.875 

2.  Oil 

14.49 

0.131 

1.694 

.824 

14-35 

O.IO2 

1-315 

1.428 

13.18 

4232.887 

0.147 

1.892 

2.028 

14.62 

0.132 

1.699 

.828 

14.28 

O.IOI 

.302 

1-415 

13.06 

42S7-8IS 

0.149 

1.900 

2.036 

14.67 

0-133 

1.696 

.825 

14.26 

O.IO4 

•331 

1.444 

13-32 

4258.477 

0.149 

1.896 

2.032 

14.64 

0.132 

1.  680 

.809 

14.14 

0.103 

.312 

1-425 

13-15 

4265.418 

0.147 

1.865 

2.001 

14.42 

0.132 

1.674 

-803 

14.09 

0.104 

.321 

1-434 

13-23 

4266.081 

0.149 

1.886 

2.O22 

14-57 

0-133 

1.685 

.814 

14.18 

O.IO3 

•305 

1.418 

13.08 

4268.915 

0.148 

1.874 

2.OIO 

14.48 

0.132 

.672 

.801 

14.07 

O.IO2 

•295 

1.408 

12.99 

4276.836 

0.146 

1.848 

1.984 

14-3° 

0.131 

•659 

.788 

13-97 

0.103 

•305 

1.418 

13.08 

4284.838 

0.147 

1-855 

.991 

14-35 

0.132 

.670 

•799 

14.06 

O.IO2 

.293 

1.406 

12.97 

4287.566 

0.147 

1-855 

.991 

14-35 

0.132 

.668 

•797 

14.04 

0.103 

•305 

1.418 

13.08 

4288.310 

0.148 

1.865 

.001 

14.42 

0.132 

.666 

•795 

14-03 

0.104 

•315 

1.428 

13.18 

4290.377 

0.147 

1-852 

.988 

14-33 

0.130 

.641 

•770 

13-83 

O.IO4 

•313 

1.426 

13.16 

4290.542 

0.148 

1.863 

•999 

14.41 

0.134 

.686 

.815 

14.18 

O.IO2 

.288 

1.401 

12.93 

4291.630 

0.148 

1.862 

.998 

14.40 

0.132 

.662 

.791 

14.00 

0.104 

.312 

I-425 

13-15 

4294.936 

0.148 

i.  86  1 

•997 

14-39 

0-133 

.673 

.802 

14.08 

O.IO4 

•3" 

1.424 

13-14 

<t>  =  S4°6 

<t>  =  6g!s 

0  -  83!6 

4196.699 

0.068 

0.892 

0.981 

12.02 

0.038 

0.504 

0.564 

n-43 

0.008 

0.132 

0.160 

10.19 

4I97-2S7 

0.069 

0.904 

0-993 

12.17 

0.037 

0-493 

0-553 

II.  21 

0.009 

0.146 

0.174 

11.08 

4203.730 

0.070 

0.916 

1.005 

12.32 

0.041 

0-543 

0-603 

12.22 

0.009 

0.145 

0.173 

1  1.  02 

4209.144 

0.070 

0.914 

1.003 

12.29 

0.041 

0-541 

0.601 

12.18 

0.008 

0.131 

0-159 

10.13 

4216.136 

0.069 

0.901 

0.990 

12.13 

0.040 

0.527 

0.587 

II.9O 

0.009 

0.145 

0.173 

11.02 

4220.509 

0.070 

0.909 

0.998 

12.23 

0.041 

0.542 

0.602 

12.  2O 

0.010 

0.161 

0.189 

12.04 

4232.887 

0.070 

0.90  1 

0.990 

12.13 

0.041 

0-539 

0-599 

12.14 

O.OIO 

0.161 

0.189 

12.04 

4257-8I5 

0.071 

0.909 

0.998 

12.23 

0-043 

0-557 

0.617 

12.51 

O.OI2 

0.189 

0.217 

13.82 

4258.477 

0.072 

0.919 

.008 

12-35 

0.042 

0-544 

0.604 

12.24 

O.OIO 

0.159 

0.187 

11.91 

4265.418 

0.073 

0-933 

.022 

12.53 

0.042 

0-544 

0.604 

12.24 

O.OII 

0.175 

0.203 

12.93 

4266.081 

0.073 

0.932 

.O2I 

12.51 

0.043 

0-553 

0.613 

12.43 

O.OI2 

0.189 

0.217 

13-82 

4268.915 

0.073 

0.929 

.Ol8 

12.48 

0.043 

0-553 

0-613 

12-43 

O.OII 

0.174 

0.202 

12.87 

4276.836 

0.072 

0.915 

.004 

12.30 

0.042 

0-541 

0.601 

12.18 

O.OIO 

0.159 

0.187 

11.91 

4284.838 

0.072 

0.915 

.004 

12.30 

0.042 

0-543 

0.603 

12.22 

O.OII 

0.176 

O.2O4 

12.99 

4287.566 

0.072 

0.913 

.002 

12.28 

0.042 

0.542 

0.602 

12.20 

0.012 

0.190 

0.218 

13.88 

4288.310 

0.074 

0.938 

.027 

12.59 

0.042 

0-541 

0.601 

12.18 

O.OIO 

0.158 

o.i  86 

11.85 

4290.377 

0.073 

0.925 

.OI4 

12.43 

0.042 

0-541 

0.601 

12.  l8 

O.OII 

0.174 

O.2O2 

12.87 

4290.542 

0.072 

0.911 

.000 

12.26 

0.042 

0.540 

0.600 

12.  l6 

O.OII 

0.174 

0.202 

12.87 

4291.630 

0.072 

0.911 

.000 

12.26 

0.041 

0.526 

0.586 

11.88 

O.OII 

0.173 

O.2OI 

12.80 

4294.936 

0.073 

0.922 

.on 

12.39 

0.043 

0.550 

0.610 

12.37 

O.OIO 

0.158 

o.i  86 

11.85 

1 8     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OP  1906-1907  —  Continued. 
Plate  w  6.     1906,  May  8,  6"  om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.4  mm.     Quality,  good. 


P-P 

IT 

<t> 

1 

seci 

0 

47.2 

o 

4-3 

5-4 

84.6 

37°8 

1.266 

O-Q 

—  27.2 

19-3 

19.6 

70.4 

9-9 

1.015 

P 

22.9 

34-3 

34-4 

55-6 

5-9 

1.005 

D 

-3-3 

49-3 

49-4 

40.6 

4-4 

1.003 

Diameter 

172.1  mm 

64-3 

64-3 

25-7 

3-7 

1.002 

Factor 

1.028 

79-3 

79-3 

10.7 

3-4 

1.002 

,- 

io!7 

*- 

25!7 

,- 

40  6 

A 

V 

P  +  ,, 

« 

A 

' 

.  +  * 

• 

A 

tl 

T)  ~\~  V, 

• 

km 

km 

. 

km 

km 

0 

km 

km 

, 

4196.699 

4I97.257 

0.146 

1.902 

2.038 

14-73 

0.128 

1.670 

.798 

14.17 

0.097 

1.266 

-378 

12.88 

4203.730 

0.146 

1.894 

2.030 

14.67 

0.130 

1.682 

.810 

14.26 

0.099 

1.288 

.400 

13.09 

4209.144 

0.147 

1.904 

2.040 

14.74 

0.130 

1.680 

.808 

14.25 

0.098 

1.273 

-385 

12.95 

4216.136 

0.146 

1.889 

2.025 

14-63 

0.127 

1.644 

.772 

13.96 

0.097 

1.264 

•376 

12.87 

4220.509 

0.148 

1.908 

2.044 

14-77 

0.130 

1.677 

.805 

14.22 

0.098 

1.270 

-382 

12.92 

4232.887 

0.148 

I-903 

2.039 

14-73 

0.130 

1.674 

.802 

14.20 

O.IOI 

1.301 

•413 

13.21 

4257.8I5 

0.151 

1.920 

2.056 

14.85 

0.132 

1.680 

.808 

14.25 

O.IO2 

1.301 

•413 

13.21 

4258.477 

0.150 

1.906 

2.042 

14-75 

0.130 

1.658 

.786 

14.07 

O.IOI 

1.283 

•395 

13-04 

4265.418 

0.149 

1.892 

2.028 

14.65 

0.130 

I.65S 

.783 

14.05 

O.IO2 

1-295 

.407 

13.16 

4266.081 

0.151 

1.912 

2.048 

14.80 

0.131 

1.664 

1.792 

14.12 

O.IO2 

1.294 

.406 

13.15 

4268.915 

0.151 

1.910 

2.046 

14.78 

0.130 

1.652 

1.780 

14.02 

0.102 

1.292 

.404 

I3-I3 

4276.836 

0.151 

1.908 

2.044 

14-77 

0-132 

1.671 

1.799 

14.17 

O.IOI 

1.279 

•391 

13.01 

4284.838 

0.150 

1.896 

2.032 

14.68 

0.131 

1.658 

1.786 

14.07 

O.IO2 

1.291 

•403 

13.12 

4287.566 

0.150 

1.893 

2.029 

14.66 

0.132 

1.665 

1-793 

14-13 

O.IOI 

1.278 

•390 

13.00 

4288.310 

0.151 

1.903 

2-039 

14-73 

0.131 

1.654 

1.782 

14.04 

O.IO2 

1.289 

.401 

13.10 

4290.377 

0.150 

1.890 

2.026 

14.64 

0.133 

I.675 

1.803 

14.20 

O.IOI 

1.276 

.388 

12.98 

4290.542 

0.150 

1.887 

2.023 

14.62 

0.131 

1.650 

1.778 

14.01 

O.IO2 

1.287 

•399 

13.08 

4291.630 

0.150 

1.886 

2.022 

14.61 

0.132 

1.662 

1.790 

14.10 

O.IO2 

1.285 

•397 

13.06 

4294.936 

0.150 

1.886 

2.O22 

14.61 

0.132 

1.662 

1.790 

14.10 

0.102 

1.284 

•396 

13-05 

*- 

5S!6 

*- 

?o!4 

,- 

84:6 

4196.699 

O.OO9 

0.153 

0.180 

13.58 

4I97.257 

0.068 

0.890 

0.978 

12.29 

0.039 

0.516 

0-574 

12.15 

0.008 

0.138 

0.165 

12-45 

4203.730 

0.068 

0.887 

0-975 

12.25 

0.039 

0.5H 

0.572 

12.  IO 

O.OIO 

0.158 

0.185 

13.96 

4209.144 

0.067 

0.873 

0.961 

12.08 

0.040 

0.527 

0.585 

12.38 

0.009 

0.154 

0.181 

13-65 

4216.136 

0.068 

0.883 

0.971 

12.  2O 

0.038 

0.500 

0.558 

ii.  81 

0.008 

0.132 

0.159 

u-99 

4220.509 

0.070 

0.905 

0-993 

12.48 

0.040 

0.524 

0.582 

12.32 

O.OII 

0.178 

0.205 

15-46 

4232.887 

0.069 

0.890 

0.978 

12.29 

0.040 

0.523 

0.581 

12.30 

0.009 

0.151 

0.178 

13-43 

4257.815 

0.072 

0.919 

1.007 

I2.6S 

0.042 

0.541 

0-599 

12.68 

O.OIO 

0.155 

0.182 

13-73 

4258.477 

0.070 

0.896 

0.984 

12-37 

0.042 

0.540 

0.598 

12.66 

O.OIO 

0.161 

o.i  88 

14.18 

4265.418 

0.071 

0.904 

0.992 

12.46 

0.041 

0.528 

0.586 

12.40 

0.009 

0.148 

O.I7S 

13.20 

4266.081 

0.072 

0.916 

1.004 

12.62 

0.042 

0-539 

0-597 

12.63 

O.OII 

0.171 

0.198 

14.94 

4268.915 

0.072 

0-915 

1.003 

1  2.  60 

0.042 

0-539 

0-597 

12.63 

0.008 

0.134 

0.161 

12.14 

4276.836 

0.072 

0.914 

i.  002 

J2-59 

0.041 

0.528 

0.586 

12.40 

0.009 

0.148 

o.i7S 

13.20 

4284.838 

0.071 

0.900 

0.988 

12.42 

0.041 

0.526 

0.584 

12.36 

O.OIO 

o.  166 

o.i93 

14.56 

4287.566 

0.072 

0.912 

I.OOO 

12.57 

0.042 

0-538 

0.596 

12.61 

0.009 

0.147 

0.174 

13-13 

4288.310 

0.071 

0.898 

0.986 

12.39 

0.041 

0.526 

0.584 

12.36 

O.OIO 

0.153 

0.180 

13.58 

4290.377 

0.072 

0.910 

0.998 

12.54 

0.041 

0-525 

0.583 

12.34 

0.009 

0.139 

o.i  66 

12.52 

4290.542 

0.072 

0.909 

0.997 

12.53 

0.044 

0-560 

0.618 

13.08 

0.009 

o.i45 

0.172 

12.98 

4291.630 

0.072 

0.909 

0.997 

12.53 

0.043 

0.548 

0.606 

12.83 

0.008 

.  0.128 

0.155 

11.69 

4294.936 

0.072 

0.909 

0-997 

12.53 

0.043 

0-547 

0.605 

1  2.80 

O.OIO 

0.150 

0.177 

13-35  . 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1906-1907. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  8.     1906,  May  19,  ioh  3om  G.  M.  T.    Measured  by  A.  on  G.    Distance  from  Limb  2.3  mm.    Quality,  good. 


p-p 


f 


sec  7 


O 
0-0 

p 

D 


58.0 

—  16.4 

19-0 

—  2.O 


Diameter  179.2  mm 
Factor        1.028 


14.6 

14.7 

75-3 

8.1 

I.OIO 

30.9 

31.0 

59-o 

4.0 

I.OO2 

44-6 

44-6 

45-4 

2.9 

I.OOI 

59-6 

59-6 

30.4 

2.4 

I.OOI 

74-6 

74.6 

iS-4 

2.1 

I.OOI 

90.9 

89.1 

o-9 

2.0 

I.OOI 

0= 

o:. 

0  = 

,5% 

0  = 

30!4 

A 

V 

.+., 

1 

A 

V 

.  +  ., 

1 

A 

1 

,  +  •> 

1 

4196.699 

0.144 

km 
1.877 

km 
2.016 

O 

I4.3I 

0.136 

km 
1.767 

km 
1.901 

O 

14.01 

0.116 

km 
I.5I8 

km 
1.642 

O 

I3-52 

4I97-257 

0.150 

I-95I 

2.090 

14.84 

0.142 

1.858 

1.992 

14.68 

0.116 

I.S2I 

1.645 

13-54 

4203.730 

4209.144 

0.154 

2.010 

2.149 

15.26 

0.138 

1.779 

I.9I3 

14.10 

0.116 

I-5I7 

1.641 

I3-5I 

4216.136 

0.144 

1.865 

2.004 

14-23 

0.136 

1-773 

1.907 

14.06 

O.I  2O 

1.561 

1.685 

13-87 

4220.509 

0.150 

1.944 

2.083 

14.79 

0.140 

1-852 

1.986 

14.64 

0.122 

1-574 

1.698 

13.98 

4232.887 

0.152 

1.963 

2.102 

14.92 

0.146 

1.920 

2.054 

15-14 

0.126 

J-545 

1.669 

13-74 

4257-8I5 

0.148 

1.897 

2.036 

14.46 

0.144 

1.906 

2.040 

15.04 

0.124 

1.714 

14.11 

4258.477 

0.146 

I.87I 

2.010 

14.27 

0.142 

1.866 

2.OOO 

14.74 

0.128 

1.639 

1.763 

I4-5I 

4265.418 

0.152 

1-952 

2.091 

14-85 

0.146 

1.908 

2.042 

15.05 

0.120 

1.540 

1.664 

13.70 

4266.081 

0.152 

1-945 

2.084 

14.80 

0.140 

1.829 

1.963 

14.47 

0.126 

1.601 

I-725 

14.20 

4268.915 

0.150 

1-930 

2.069 

14.69 

0.136 

1.790 

1.924 

14.18 

0.116 

1.568 

1.692 

13-93 

4276.836 

0.152 

1.936 

2.075 

14-73 

0.138 

1.818 

1-952 

14.38 

0.118 

1-583 

1.717 

4284.838 

0.156 

1.964 

2.103 

14-93 

0.140 

1.832 

1.966 

14.49 

O.I  2O 

1.601 

1.725 

14.20 

4287.566 

0.152 

1.918 

2-057 

14.61 

0.144 

1.883 

2.OI7 

14.87 

O.I  2O 

1.607 

I-73I 

I4-2S 

4288.310 

0.154 

1-950 

2.089 

14.83 

0.136 

1.768 

1.902 

14.02 

0.122 

1-540 

1.664 

I3-70 

4290-377 

0.148 

1.872 

2.  Oil 

14.28 

0.150 

1.881 

2.OI5 

14-85 

0.128 

1.613 

1-737 

I4-30 

4290.542 

0.154 

1.948 

2.087 

14.82 

0.148 

1.850 

1.984 

14.62 

0.130 

1.627 

i-75i 

14.41 

4291.630 

0.152 

1.940 

2.079 

14.76 

0.148 

1.850 

1.984 

14.62 

0.130 

1.623 

1-747 

14.38 

4294.936 

0.146 

1.835 

1-974 

14.02 

0.142 

1.770 

1.904 

14-03 

0.128 

1.598 

1.722 

14.17 

0  = 

4S!4 

0  = 

S9°.° 

0  = 

75:3 

4196.699 

O.IOO 

1.214 

1.320 

13-35 

0.064 

0.825 

0.908 

12.52 

O.O26 

0-334 

0-383 

10.72 

4I97-257 

0.092 

1.189 

1.295 

I3-09 

0.066 

0.871 

0-954 

13-15 

O.O26 

0.330 

0-379 

10.60 

4203.730 

4209.144 


0.096 

1-243 

1-349 

13-64 

0.066 

0.862 

0-945 

13.03 

0.032 

0.392 

0.441 

12.34 

4216.136 

0.094 

1.  212 

1.318 

13-33 

0.068 

0.890 

0-973 

13-41 

O.O28 

0.358 

0.407 

"•39 

4220.509 

0.094 

1.  221 

I-327 

I3-42 

0.066 

0.874 

0-957 

13-19 

0.030 

0.391 

0.440 

12.31 

4232.887 

0.092 

1.186 

1.292 

13.06 

0.064 

0.846 

0.929 

12.80 

0.030 

0-393 

0.442 

12.37 

4257-8I5 

O.IOO 

1.279 

1-385 

14.00 

0.072 

0.910 

0-993 

13.69 

0.034 

0.438 

0.487 

13-63 

4258.477 

0.094 

1.  211 

I-3I7 

I3-32 

0.068 

0.873 

0.956 

13.18 

0.032 

0.421 

0.470 

I3-I5 

4265.418 

0.098 

1.247 

1-353 

13.68 

0.066 

0.836 

0.919 

12.67 

0.030 

0.383 

0-432 

12.09 

4266.081 

0.092 

I-I75 

1.281 

12.95 

0.064 

0.811 

0.894 

12.32 

0.032 

0.401 

0.450 

12.59 

4268.915 

0.098 

•239 

1-345 

13.60 

0.070 

0.900 

0.983 

13-55 

0.032 

0.415 

0.464 

12.98 

4276.836 

0.096 

.230 

1.336 

I3-SI 

0.068 

0.870 

0-953 

13-14 

0.030 

0-389 

0.438 

12.25 

4284.838 

0.094 

.197 

1-303 

I3-I7 

0.070 

0.86  1 

0-944 

13.01 

0.036 

0.465 

0.514 

14-38 

4287.566 

0.096 

.2IO 

1.316 

I3-30 

0-074 

0.890 

0-973 

13-41 

0.034 

0.446 

0-495 

13-85 

4288.310 

0.098 

.231 

1-337 

I3-52 

0.068 

0-933 

1.016 

14.00 

0.032 

0.432 

0.481 

13-46 

4290.377 

0.096 

.219 

I-325 

13-39 

0.070 

0.845 

0.928 

12.79 

0.034 

0.446 

0-495 

13-85 

4290.542 

0.092 

.169 

1-275 

12.89 

0.072 

0.874 

0-957 

13-19 

O.O26 

0.330 

0-379 

10.60 

4291.630 

0.096 

.216 

1.322 

I3-36 

0.072 

0.899 

0.982 

13-54 

0.034 

0.432 

0.481 

13-46 

4294.936 

0.096 

.219 

I-325 

13-39 

0.072 

0.902 

0.985 

13-58 

0.032 

0-399 

0.448 

12.53 

20     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD    OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 

TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  ia  19.     1906,  June  12,  6h  45m  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.2  mm.     Quality,  good. 


Q        80.8 

14.9 

14.9 

75- 

3-i 

i.  002 

O-n     60.4 

29.9 

29.9 

60. 

1.6 

I.OOO 

P             II.  2 

44-9 

44-9 

45- 

i.i 

1.  000 

D           0.9 

59-9 

59-9 

30- 

0.9 

I.OOO 

Diameter  169.1  mm 

74-9 

74-9 

IS- 

0.8 

I.OOO 

Factor        1.027 

89.9 

89.9 

o. 

[        0.8 

I.OOO 

0  •=  °!i 

0  =  isti 

<t>  =  3o!i 

A 

V 

»  +  »! 

1 

A 

V 

»  +  »! 

£ 

A 

» 

t>  +  t>, 

s 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.150 

1-945 

2.078 

14-75 

0.139 

1.809 

1.941 

14.27 

0.118 

1-533 

1.656 

13-59 

4197.257 

0.152 

1.970 

2.103 

14-93 

0.140 

1.820 

1.952 

14-35 

0.118 

1-533 

1.656 

13-59 

4203.730 

0.149 

1.932 

2.065 

14.66 

0.140 

1.817 

1.949 

14-32 

O.I22 

1-583 

1.706 

14.00 

4209.144 

0.148 

1.919 

2.052 

14-57 

0.144 

1.864 

1.996 

14.68 

O.I2I 

1-567 

1.690 

13-87 

4216.136 

0.150 

1-937 

2.070 

14.70 

0.137 

1.770 

1.902 

13-99 

0.116 

1.498 

1.621 

13-30 

4220.509 

0.147 

1.896 

2.029 

14.40 

o.i44 

1.817 

1.949 

14.32 

O.Iig 

1-532 

I.655 

13-58 

4232.887 

0.156 

1.890 

2.023 

I4-36 

0.144 

1.847 

1.979 

14-55 

O.I22 

1-565 

1.688 

13-85 

4257.815 

0.150 

1.904 

2.037 

14.46 

0.140 

1-773 

1.905 

14.01 

0.124 

1-574 

1.697 

13-93 

4258.477 

0.151 

1.914 

2.047 

14-53 

0.146 

1.848 

1.980 

14.56 

0.123 

1-563 

1.686 

13.84 

4265.418 

0.152 

1.926 

2.059 

14.62 

0.146 

1.848 

1.980 

14-56 

O.I24 

1-57' 

1.694 

13.90 

4266.081 

0.150 

1.901 

2.044 

I4-5I 

0.143 

1.809 

1.941 

14.27 

O.I2I 

1-530 

1-653 

13-56 

4268.915 

0.151 

1.910 

2.043 

14.50 

0.140 

1.769 

1.901 

13.98 

O.I24 

1-570 

1.693 

13.89 

4276.836 

0.152 

1.914 

2.047 

14-53 

0.145 

1.822 

1-954 

14-37 

O.I26 

1.588 

1.711 

14.04 

4284.838 

0.152 

1.910 

2.043 

14.50 

0-145 

1.822 

1-954 

14.37 

0.122 

1-534 

1-657 

13.60 

4287.566 

0.154 

1-937 

2.070 

14.70 

0.142 

1.782 

1.914 

14.07 

0.124 

I.556 

1.679 

13-78 

4288.310 

0-153 

1.919 

0.052 

14-57 

0.142 

1.782 

1.914 

14.07 

O.I24 

1-556 

1.679 

13-78 

4290.377 

0.154 

1.932 

2.065 

14.66 

0.141 

1.771 

I-903 

14.00 

O.I22 

1-529 

1.652 

13-56 

4290.542 

0.150 

1.881 

2.014 

I4-30 

0.146 

1.830 

1.962 

14.42 

0.125 

1.569 

1.692 

13.88 

4291.630 

0.152 

1-905 

2.038 

14.47 

0.146 

1.830 

1.962 

14.42 

O.I26 

1-574 

1.697 

13-93 

4294.936 

0.156 

1-954 

2.089 

14.82 

0.144 

1.804 

1.936 

14-23 

O.I2I 

i-Si3 

1.636 

13-42 

<t>  =  4S:i 

0  =  &>:i 

*  =  75?i 

4196.699 

0.088 

I-I45 

1.250 

12-57 

0.058 

0-755 

0-835 

11.89 

0.028 

0.364 

0.414 

u-43 

4197-257 

0.088 

1.  145 

1.250 

12.57 

0.059 

0.768 

0.848 

1  2.08 

0.028 

0.364 

0.414 

n-43 

4203.730 

0.091 

1.181 

1.286 

12-93 

0.059 

0.766 

0.846 

12.05 

0.031 

0.403 

0-453 

12.51 

4209.144 

0.092 

1.191 

1.296 

13-03 

0.06  1 

0.790 

0.870 

12.38 

0.031 

0.402 

0.452 

12.48 

4216.136 

0.090 

1.162 

1.267 

12.74 

0.058 

0.751 

0.831 

11.84 

0.030 

0.387 

0-437 

12.07 

4220.509 

0.092 

1.186 

1.291 

12.98 

0.062 

0-799 

0.879 

12.52 

0.032 

0.413 

0-463 

12.78 

4232.887 

0.090 

I-I55 

1.260 

12.67 

0.063 

0.809 

0.889 

12.66 

0.033 

0.423 

0-473 

13.06 

4257-815 

0.095 

1.209 

I-3H 

13.21 

0.064 

0.814 

0.894 

12.73 

0.034 

0.433 

0.483 

13-34 

4258.477 

0.094 

1.191 

1.296 

13-03 

0.062 

0.788 

0.868 

12.36 

0.033 

0.419 

0.469 

12.95 

4265.418 

0.092 

1.166 

1.271 

12.78 

0.063 

0.798 

0.878 

12.50 

0.032 

0.406 

0.456 

12.59 

4266.081 

0.094 

1.190 

1-295 

13.02 

0.065 

0.824 

0.904 

12.87 

0.034 

0.431 

0.481 

13.28 

4268.915 

0.093 

I-I73 

1.278 

12.85 

0.062 

0-783 

0.863 

12.29 

0.033 

0.418 

0.468 

12.92 

4276.836 

0.091 

1.149 

1-254 

12.  6l 

0.062 

0.783 

0.863 

12.29 

0.034 

0.430 

0.480 

13-25 

4284.838 

0.094 

1.183 

1.288 

12.95 

0.065 

0.817 

0.897 

12.78 

0.033 

0.416 

0.466 

12.87 

4287.566 

0.094 

1.182 

1.287 

12.94 

0.065 

0.805 

0.885 

12.60 

0.033 

0.415 

0.465 

12.84 

4288.310 

0.093 

1.169 

1.274 

12.81 

0.064 

0.805 

0.885 

12.60 

0-033 

0.415 

0.465 

12.84 

4290.377 

0.094 

1.181 

1.286 

12.93 

0.062 

0-779 

0.859 

12.23 

0-033 

0.414 

0.464 

12.81 

4290.542 

0.094 

1.180 

1.285 

12.92 

0.064 

0.804 

0.884 

12-59 

0.034 

0.427 

0.477 

I3-I7 

4291.630 

0.094 

1.179 

1.284 

12.91 

0.064 

0.804 

0.884 

12-59 

0.034 

0.426 

0.476 

13-14 

4294.936 

0.094 

1.179 

1.284 

12.91 

0.066 

0.827 

0.907 

12.92 

0.032 

0.401 

0.451 

12.45 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


21 


Plate 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
20.     1906,  June  12,  7h  i5m  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.2  mm.     Quality,  good. 

p— P          T  0  i)  seci 


O         80.9 

o-n      6.5 

29-9 

29.9 

p       ii.  i 

44-9 

44-9 

D           0.9 

59-9 

59-9 

Diameter  169.1  mm 

74-9 

74-9 

Factor        1.027 

89-9 

89.9 

60. 1 

30.1 

O.I 


1.6 
i.i 
0.9 
0.8 
0.8 


I.OOO 
I.OOO 
I.OOO 
I.OOO 
I.OOO 


0  = 

o:< 

0  = 

is!i 

0  = 

3o!i 

A 

•o 

M-., 

« 

A 

V 

v  +  v1 

f 

A 

» 

»+»! 

{ 

km 

km 

. 

km 

km 

0 

km 

km 

O 

4196.699 

0.146 

.901 

2.034 

14-44 

0-137 

1-779 

1.911 

14.05 

0.116 

1.508 

1.631 

I3-38 

4197-257 

0.147 

.911 

2-044 

I4-5I 

0-139 

1.800 

1-932 

14.21 

0.119 

1-544 

1.667 

13-68 

4203.730 

0.152 

.971 

2.104 

14.94 

0.141 

1.822 

1-954 

14-37 

O.I2I 

1.566 

1.689 

13.86 

4209.144 

0.151 

•950 

2.083 

14-79 

0.140 

i.  806 

1.938 

14-25 

O.I22 

1-575 

1.698 

13-93 

4216.136 

0.148 

.910 

2.043 

14.50 

0.138 

1.782 

1.914 

14.07 

O.IlS 

I-523 

1.646 

I3-5I 

4220.509 

0.150 

•935 

2.068 

14-68 

0.142 

1.826 

1.958 

14.40 

O.IlS 

1.521 

1.644 

13-49 

4232.887 

0.154 

•975 

2.108 

U-97 

0.142 

1.820 

1-952 

14-35 

0.122 

1-563 

1.686 

13-84 

4257-815 

0.156 

.982 

2.II5 

I5.O2 

0.144 

1.828 

1.960 

14.41 

O.I24 

1-575 

1.698 

13-93 

4258.477 

0.152 

•929 

2.062 

14.64 

0.143 

1.813 

1-945 

14.30 

O.I22 

1-550 

1-673 

13-73 

4265.418 

0-153 

•939 

2.072 

14.71 

0.140 

1.772 

1.904 

14.00 

O.I2I 

1-530 

I-653 

I3-56 

4266.081 

0-153 

•939 

2.072 

14.71 

0.144 

1.817 

1-949 

14.32 

0.123 

1.551 

1.674 

13-74 

4268.915 

0.152 

•924 

2.057 

14.60 

0.143 

1.805 

1-937 

14.24 

O.I22 

J-539 

1.662 

13.64 

4276.836 

0-154 

•945 

2.078 

14-75 

0.143 

1.803 

1-935 

14.23 

0.122 

1-537 

i.  660 

13.62 

4284.838 

0.150 

.890 

2.023 

14.36 

0.142 

1.786 

1.918 

14.10 

O.I24 

1-559 

1.682 

13.80 

4287.566 

0.152 

.910 

2.043 

14-50 

0.142 

1.781 

I-9I3 

14.07 

O.I22 

1-530 

1-653 

I3-56 

4288.310 

0.154 

•931 

2.064 

14.65 

0.144 

1.805 

1-937 

14.24 

O.I2I 

I-5I9 

1.642 

13-47 

4290-377 

0.152 

.909 

2.042 

14-49 

0.142 

1.780 

1.912 

14.06 

O.I  2O 

1-508 

1.631 

13-38 

4290.542 

0-153 

.920 

2-053 

I4-58 

0-143 

1.794 

1.926 

14.16 

O.I  2O 

1-504 

1.627 

13-35 

4291.630 

0.152 

.909 

2.042 

14.49 

0.142 

1.780 

1.912 

14.06 

0.122 

1-528 

1.651 

13-55 

4294.936 

0.156 

1-954 

2.087 

14.82 

0.140 

1-753 

1.885 

13.86 

O.I  21 

I-5I7 

1.640 

13.46 

0  = 

4* 

0  = 

•* 

4196.699 

0.086 

1.116 

1.  221 

12.28 

0.056 

0.730 

0.810 

11-54 

4197-257 

0.088 

1.141 

1.246 

12-53 

0.058 

0.752 

0.832 

11.85 

4203.730 

0.090 

1.165 

1.270 

12.77 

0.059 

0.765 

0.845 

12.03 

4209.144 

0.091 

.178 

1.283 

12.90 

0.060 

0-775 

0-855 

12.18 

4216.136 

0.088 

-136 

I.24I 

12.48 

0.058 

0.749 

0.829 

11.81 

4220.509 

0.089 

-145 

1.250 

12-57 

0.062 

0.799 

0.879 

12.52 

4232-887 

0.092 

.179 

1.284 

12.91 

0.062 

0.797 

0.877 

12.49 

4257-815 

0.096 

.217 

1-322 

13.29 

0.066 

0-839 

0.919 

13.09 

4258.477 

0.094 

•193 

1.298 

13-05 

0.064 

0.813 

0.893 

12.72 

4265.418 

0.091 

•151 

1.256 

12.63 

0.063 

0.801 

0.881 

12-55 

4266.081 

0.096 

•215 

1.320 

13-27 

0.065 

0.823 

0-903 

12.86 

4268.915 

0-093 

•175 

1.280 

12.87 

0.063 

0-797 

0.877 

12.49 

4276.836 

0-093 

•173 

1.278 

12.85 

0.062 

0.785 

0.865 

12.32 

4284.838 

0.092 

•159 

.262 

12.69 

0.06  1 

0.770 

0.850 

1  2.  1  1 

4287.566 

0.090 

.132 

•237 

12.42 

0.064 

0.804 

0.884 

12-59 

4288.310 

0.094 

.181 

.286 

12-93 

0.062 

0-779 

0.859 

12.23 

4290.377 

0.091 

.141 

.246 

12-53 

0.063 

0.790 

0.870 

12.39 

4290.542 

0.091 

.141 

.246 

"•S3 

0.062 

0-775 

0-855 

12.18 

4291.630 

0.091 

.141 

.246 

12-53 

0.064 

0-799 

0.879 

12.52 

4294.936 

0.094 

.179 

.284 

12.91 

0.063 

0.789 

0.869 

12.38 

22    AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  — Continued. 
Plate  w  21.     1906,  June  12,  7"  45™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.2  mm.     Quality,  good. 


P-P 


0 

o-n 
p 

D 


80.9 
6-5 

it. i 
0.9 


Diameter  169.1  mm 
Factor        1.027 


14.9 

14.9 

75-i 

3-2 

.002 

29.9 

29.9 

60.  i 

1.6 

.OOO 

44.9 

44-9 

45-  1 

i.i 

.OOO 

59.9 

59-9 

30.1 

0.9 

.000 

73-9 

73-9 

16.1 

0.8 

.000 

74-9 

74-9 

iS-i 

0.8 

.000 

89.9 

89.9 

O.I 

0.8 

.000 

#-* 

0  -  rfi 

*  -  .a:, 

A 

V 

,  +  ,, 

1 

A 

V 

,  +  „ 

i 

A 

V 

V  +  II  j 

i. 

4196.699 

0.146 

km 
.897 

km 
2.030 

0 

14.41 

0.138 

km 
1.794 

km 
1.926 

D 
I4.I6 

0.137 

km 

.780 

km 
1.912 

14-13 

4197-257 

0.148 

•923 

2.056 

14.60 

0-139 

1.801 

1-933 

14.21 

0.138 

.790 

1.922 

14.20 

4203.730 

0.149 

•934 

2.067 

14.67 

0.141 

1-823 

1-955 

14.38 

0.140 

.812 

1.944 

14-36 

4209.144 

0.152 

•963 

2.096 

14.88 

0.142 

.831 

1.963 

14.21 

0.139 

.796 

1.928 

14.24 

4216.136 

0.148 

.910 

2.043 

14-50 

0-139 

•793 

1.925 

I4.l6 

0.138 

•779 

I.9II 

14.12 

4220.509 

0.150 

•934 

2.067 

14.67 

0.140 

.801 

1-933 

14.21 

0.139 

.791 

1.923 

14  21 

4232.887 

0.152 

•942 

2.075 

M-73 

0.143 

.822 

1-954 

14-37 

0-143 

•833 

1.965 

I4.52 

4257-SiS 

0.154 

-953 

2.086 

14.81 

0.143 

.825 

1-957 

14-39 

0.145 

.840 

1.972 

14-57 

4258.47? 

0.152 

.928 

2.061 

14.63 

0.142 

.800 

1.932 

14.21 

0.143 

.815 

1.947 

14.38 

4265.418 

0.154 

•949 

2.082 

14.78 

0.144 

.822 

1-954 

14-37 

0.144 

.823 

1-955 

14.44 

4266.081 

0.152 

•924 

2-057 

14.60 

0-143 

.808 

1.940 

14.27 

0.142 

.805 

1-937 

I4-3I 

4268.915 

0.150 

.898 

2.031 

14.42 

0.143 

•803 

1-935 

I4.23 

0.144 

.822 

1-954 

14.44 

4276.836 

0-153 

•930 

2.063 

14.65 

0.145 

.824 

1.956 

14.38 

0.142 

•794 

1.926 

14.23 

4284.838 

0-153 

1.923 

2.056 

14.60 

0.142 

.786 

1.918 

I4.IO 

0.144 

•815 

1.947 

14.38 

4287.566 

0.154 

1.936 

2.069 

14.69 

0.143 

•795 

1.927 

14.17 

0.146 

•835 

1.967 

14-53 

4288.310 

0.154 

1-935 

2.068 

14.68 

0.143 

-795 

1.927 

14.17 

0.140 

.760 

1.892 

13.98 

4290.37? 

0.150 

1.885 

2.018 

14-33 

0.145 

1.819 

I-95I 

14-35 

0.143 

•794 

1.926 

14.23 

4290.542 

0.152 

1.907 

2.040 

14.48 

0.142 

1.780 

1.912 

I4.O6 

0.142 

.784 

1.916 

14.16 

4291.630 

0-153 

1.920 

2.053 

14.58 

0.144 

1.804 

1.936 

14.24 

0.144 

.809 

1.941 

14-34 

4294-936 

0.154 

1.929 

2.062 

14.64 

0.141 

1.768 

1.900 

13-97 

0.145 

.818 

1.950 

14.41 

\ 

<t>  =  3°!' 

.  =  45!, 

<t>  —  6o°i 

*  =  K°.< 

A 

A 

V 

.  +  ,, 

£ 

A 

s 

.  +  ,, 

£ 

A 

V 

M-i 

£ 

A 

« 

,  +  ,, 

« 

km 

km 

. 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.116 

I.5I5 

1.63* 

13-44 

0.088 

1.146 

1.251 

12.58 

0.056 

0.727 

0.8o; 

11.49 

0.027 

0-354 

0.40.1 

11.15 

4197.257 

0.120 

1-555 

1.67? 

13-77 

0.087 

1.131 

i.23C 

12.43 

0.058 

0.749 

0.82C 

11.81 

0.029 

0-375 

0.42; 

"•73 

4203.730 

O.I  2O 

•552 

1.675 

13-74 

0.090 

1.165 

I.27C 

>    12.77 

0.06  1 

0.788 

0.86* 

12.36 

0.030 

0.389 

0-43? 

12.12 

4209.144 

O.I  2O 

•550 

I-673 

13-73 

0.090 

1.164 

I.26{ 

12.76 

0.06  1 

0.787 

0.86; 

12.35 

0.030 

0.389 

o-43? 

12.12 

42I6.I36 

0.118 

•523 

1.641 

13-51 

0.090 

1.162 

1.26- 

12.74 

0.057 

0-735 

0.8  1  ; 

ii.  61 

0.029 

0-374 

0.424 

II-7I 

4220.509 

O.I  2O 

•546 

1.66? 

13-70 

0.090 

1.161 

I.26( 

'     12.73 

0.060 

0-774 

0.854 

12.  16 

0.031 

0.398 

0.44? 

12-37 

4232.887 

O.I2I 

•552 

1.67; 

J3-75 

0.095 

1.213 

I.3IJ 

!     13.26 

0.06  1 

o.779 

o.85c 

12.23 

0.032 

0.423 

0-473 

13.04 

4257.815 

0.124 

-568 

1.691 

13.88 

0.098 

1.244 

I-34C 

1     13-57 

0.064 

0.810 

o.Sgc 

i    12.68 

0.034 

0.438 

0.48? 

13-47 

4258.477 

O.I22 

•543 

i.66f 

13-67 

0.093 

1.189 

1.29^ 

I     13-01 

0.062 

0.785 

0.86  = 

12.32 

0.034 

0.409 

0-45? 

12.67 

4265.418 

O.I22 

•54i 

1.664 

13-65 

0.094 

1.187 

1.29: 

12.99 

0.062 

0.784 

0.86^ 

12.30 

0.032 

0.404 

0-454 

12-54 

4266.081 

0.123 

•555 

1.678 

13-78 

0.092 

1.166 

1.271 

12.78 

0.064 

0.808 

0.88? 

12.65 

0.031 

0-434 

0.484)    13.36 

4268.915 

0.  121 

•529 

1.65: 

13-56 

0.092 

1.165 

I.27C 

>     12.77 

0.060 

0-759 

o.83c 

n-95 

0.034 

0-454 

0.504 

13.92 

4276.836 

O.I22 

•537 

i.66c 

>    13.62 

0.093 

1.174 

I.27C 

1     12.86 

0.064 

0.806 

o.88( 

12.62 

0.032 

0.419 

0.46$ 

12-95 

4284.838 

O.I2I 

-524 

1.64; 

13-52 

0.094 

1.182 

1.28- 

'     12.94 

0.062 

0.784 

0.864 

12.30 

0.032 

0.403 

0-453 

12.51 

4287.566 

O.I22 

•53° 

1-65; 

13-56 

0.093 

1.167 

1.27: 

12.79 

0.064 

0.801 

0.881 

12.55 

0.034 

0.428 

0.478 

13.20 

4288.3IO 

0.122 

•529 

1.65: 

13-56 

0.092 

1.157 

1.26: 

12.69 

0.062 

0-779 

o.8Sc 

12.23 

0.034 

0.428 

0.478!    13.20 

4290.377 

0.126 

•578 

1.701 

13.96 

0.093 

1.167 

1.27: 

12.79 

0.061 

0.769 

0.84? 

12.09 

0.032 

0.402 

0.452 

12.48 

4290.542 

0.123 

•543 

I.66C 

13-67 

0.091 

1.146 

1.251 

12.58 

0.064 

0.800 

o.88c 

>    12.53 

0.031 

0.388 

0.438 

12.09 

4291.630 

0.124 

1-553 

i.6jt 

13-75 

0.090 

1.131 

I.23< 

>     12.43 

0.063 

0.789 

o.86c 

12.38 

0.034 

0.428 

0-47* 

13.20 

4294.936 

O.I22 

I-527 

i.osc 

13-54 

0.092 

I.26< 

>     12.67 

0.062 

0.779 

0-85? 

12.23 

0.034 

0.427 

0.473 

I3-I7 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  ID  23.     1906,  June  15,  6h  om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.3  mm.     Quality,  good. 

p— P          T  0  1          secTi 


Q 

83-7 

15.0 

iS-o 

75-0 

4.5 

I.OO3 

0-0 

9-3 

31.0 

31.0 

59-° 

2-3 

1.  001 

P 

9-9 

4S-o 

4S-° 

45-° 

i-7 

I.OOO 

D 

1.2 

60.0 

60.0 

30.0 

1.4 

I.OOO 

Diameter 

169.3  mm 

7S-o 

7S-° 

15.0 

1.2 

I.OOO 

Factor 

1.028 

90.0 

90.0 

0.0 

1.2 

I.OOO 

<*>  = 

o°o 

0  = 

is!o 

<t>  = 

3°!° 

A 

V 

v  +  vl 

1 

A 

» 

»+»i 

£ 

A 

V 

»  +  T, 

£ 

km 

km 

0 

km 

km 

0 

km 

km 

o 

4196.699 

0.146 

1.900 

2-033 

14-43 

0.138 

1-797 

.929 

14.18 

0.118 

•536 

1.659 

13.60 

4197-257 

0.148 

1.925 

2.058 

14.61 

0.138 

1-797 

•929 

14.18 

0.119 

•547 

1.670 

13.69 

4203.730 

0.149 

1.936 

2.069 

14.69 

0.140 

1.815 

•947 

14-31 

0.119 

•545 

1.668 

13-67 

4209.144 

0.150 

1-913 

2.046 

14-53 

0.141 

1.824 

•956 

14.38 

O.I  21 

•567 

1.690 

13-85 

4216.136 

0.148 

1.893 

2.026 

14-38 

0138 

1-785 

.917 

14.09 

O.II8 

.526 

1.649 

13-52 

4220.509 

0.150 

1.903 

2.036 

14-45 

0.140 

.808 

.940 

14.26 

O.IlS 

•524 

1.647 

13-50 

4232.887 

0.150 

1-903 

2.036 

14-45 

0.142 

.825 

•957 

14.38 

O.I22 

.566 

1.689 

13-85 

4257-815 

0.152 

1.930 

2.063 

14-65 

0.143 

.817 

•949 

14-33 

0.122 

•547 

1.670 

13.69 

4258.477 

0.153 

1.948 

2.081 

14-77 

0.143 

.817 

•949 

14.33 

O.I23 

1-557 

i.  680 

13-77 

4265.418 

0.154 

1.952 

2.085 

14.80 

0.145 

.832 

.964 

14.44 

O.I22 

1-544 

1.667 

13-67 

4266.081 

0.152 

1.926 

2.059 

14.62 

0.142 

.800 

•932 

14.20 

0.123 

1-554 

1.677 

13-75 

4268.915 

0.153 

1-935 

2.068 

14.68 

0.144 

.820 

•952 

14.35 

O.I24 

i-57i 

1.694 

13-88 

4276.836 

0.156 

1.969 

2.102 

14.92 

0.140 

.768 

1.900 

13.96 

O.I2I 

1.526 

1.649 

13-52 

4284.838 

0-153 

1.928 

2.o6l 

14.63 

0.142 

.786 

1.918 

14.10 

0.123 

1.548 

1.671 

13-70 

4287.566 

0.153 

1.927 

2.o6o 

14.62 

0.143 

.798 

1-930 

14.18 

O.I2I 

1.522 

1.645 

13-49 

4288.310 

0.152 

1.909 

2.042 

14.50 

0.143 

•798 

1.930 

14.18 

0.123 

1.546 

1.669 

13.68 

4290-377 

0.152 

1.909 

2.042 

14-50 

0.142 

-783 

I-9IS 

14.08 

0.124 

1.560 

1.683 

13.80 

4290.542 

0.151 

1.898 

2.031 

14.42 

0.142 

-783 

I-9I5 

14.08 

O.I22 

'•535 

1.658 

13-59 

4291.630 

0.152 

1.907 

2.040 

14.48 

0.144 

.807 

1-939 

14-25 

0.123 

I-S4S 

1.668 

13-67 

4294.936 

0.152 

1.907 

2.O40 

14.48 

0.142 

.781 

1.912 

14.05 

O.I24 

1-558 

i.  68  1 

13-78 

0  = 

45!° 

<t>  = 

S9°.° 

<t>  = 

is'.o 

4196.699 

0.087 

1.132 

1-237 

12.42 

0.057 

0-743 

0.825 

"•37 

O.O29 

0.380 

0.430 

n.8o 

4197-257 

0.090 

1.163 

1.268 

12.73 

0.057 

0-743 

0.825 

11-37 

0.030 

0.391 

0.441 

12  IO 

4203.730 

0.088 

I-I45 

1.250 

12-55 

0.059 

0.766 

0.848 

11.69 

O.028 

0.365 

0.415 

11.38 

4209.144 

0.092 

1.191 

.296 

13.01 

0.060 

0.776 

0.858 

11.83 

0.030 

0.389 

0-439 

I2.O4 

4216.136 

0.087 

1.  122 

.227 

12.32 

0.058 

0.750 

0.832 

11.47 

O.O29 

0.378 

0.428 

11.74 

4220.509 

0.088 

I-I37 

.242 

12-47 

0.061 

0.787 

0.869 

11.98 

0.030 

0.388 

0.438 

12.01 

4232.887 

0.090 

I-IS4 

•259 

12.64 

0.062 

0.799 

0.881 

12.14 

0.031 

0.398 

0.448 

12.29 

4257-815 

0.092 

I.I7O 

•275 

12.80 

0.062 

0.791 

0.873 

12.03 

0.031 

0.396 

0.446 

12.23 

4258.477 

0.094 

I-I95 

.300 

I3-05 

0.062 

0.791 

0.873 

12.03 

0.030 

0-379 

0.429 

11.77 

4265.418 

0.092 

1.165 

1.270 

12.75 

0.063 

0.800 

0.882 

12.  16 

0.032 

0.386 

0.436 

11.96 

4266.081 

0.090 

I-I39 

1.244 

12.49 

0.062 

0.789 

0.871 

I2.OI 

0.034 

0.431 

0.481 

13-19 

4268.915 

0.091 

I.I5I 

1.256 

12.  6l 

0.058 

0-734 

0.8  1  6 

11.25 

0.032 

0.405 

0-455 

12.48 

4276.836 

0.092 

1.161 

1.266 

12.71 

0.062 

0.787 

0.869 

11.98 

0.032 

0.405 

0-455 

12.48 

4284.838 

0.094 

1.184 

1.289 

12.94 

0.063 

0-793 

0.875 

I  2.  06 

0.031 

0-393 

0-443 

12.15 

4287.566 

0.092 

1.158 

1.263 

12.68 

0.06  1 

0.766 

0.848 

11.69 

0.031 

0-393 

0-443 

12.15 

4288.310 

0.093 

1.164 

1.269 

12-74 

0.062 

0.780 

0.862 

11.88 

0.031 

0-393 

0-443 

12.15 

4200.377 

0.089 

1.116 

1.  221 

12.26 

0.062 

0-779 

0.861 

11.87 

0.032 

0.403 

0-453 

12.43 

4290.542 

0.090 

1.131 

1.236 

12.41 

0.060 

0-755 

0.837 

"•54 

0.032 

0.403 

0-453 

12-43 

4291.630 

0.094 

1.182 

1.287 

12.91 

0.061 

0.765 

0.847 

11.68 

0.032 

0.403 

0-453 

12.43 

4294.936 

0.090 

1.130 

1.235 

12.40 

0.065 

0.815 

0.897 

12.36 

0.031 

0.389 

0-439 

12.04 

24     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  24.     1906,  June  15,  6h  15™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.4  mm.     Quality,  good. 


P-P 


sec?) 


O 

o-n 
p 

D 


83-7 
9-3 
9.9 

1.2 


Diameter  169.5  mm 
Factor        1.030 


15.0 
30.0 

15.0 
30.0 

7S-° 
60.0 

4-5 

2.2 

1.003 
I.OOI 

45-° 
60.0 

45-o 
60.0 

4S-o 
30.0 

1.7 

J-4 

1.  000 
1.  000 

75-o 

7S-o 

15.0 

1.2 

I.OOO 

90.0 

90.0 

o.o 

1.2 

I.OOO 

<t>  —  o°o 

<t>  =  is!o 

0  =  30°o 

A 

» 

V+  Dj 

e 

A 

11 

i>  +  fl, 

£ 

A 

V 

D  +  Dj 

£ 

km 

km 

0 

km 

km 

, 

km 

km 

. 

4196.699 

0.148 

1.923 

2.056 

14.60 

0.138 

•795 

1.927 

14.16 

0.118 

1-540 

1.663 

13-63 

4197.257 

0.147 

I.QI2 

2-045 

14-52 

0.138 

•795 

1.927 

14.16 

0.117 

I.52S 

1.648 

I3-5I 

4203.730 

0.150 

1.946 

2.079 

14.76 

0.138 

•792 

1.924 

14.14 

O.I2I 

1-575 

1.698 

13.92 

4209.144 

0.150 

1.944 

2.077 

14-75 

0.140 

-815 

1.947 

14-31 

O.I  2O 

1-558 

I.68I 

I3-78 

4216.136 

0.146 

I.SgO 

2.023 

14-36 

0.138 

.790 

1.922 

14-13 

O.II8 

1.528 

1.651 

13-53 

4220.509 

0.150 

1.940 

2.073 

14.72 

0.141 

.821 

1-953 

14-35 

O.I22 

1.581 

1.704 

13-97 

4232.887 

0.152 

1-955 

2.088 

14.82 

0.142 

.827 

1-959 

14.40 

O.I22 

I-57I 

1.694 

13.89 

4257.815 

0.153 

i-95i 

2.084 

14.79 

0.145 

.848 

1.980 

M-55 

0.122 

i-553 

1.676 

13-74 

4258.477 

0.154 

1.958 

2.091 

14-85 

0.142 

1.805 

1-937 

14.24 

O.I2I 

1-541 

1.664 

13.64 

4265.418 

0-155 

1.969 

2.IO2 

14.92 

0.142 

1.802 

1-934 

14.21 

0.123 

1.562 

1.685 

13.81 

4266.081 

0.153 

1-939 

2.072 

14.71 

0.143 

1.816 

1.948 

14.32 

O.I2I 

1-537 

1.  660 

13.61 

4268.915 

0.153 

1-937 

2.O7O 

14.70 

0.142 

.801 

1-933 

14.21 

0.122 

1-548 

1.671 

13.70 

4276.836 

0.152 

1.923 

2.056 

14.60 

0.144 

.822 

1-954 

14.36 

0.123 

1-555 

1.678 

13.76 

4284.838 

0.153 

I-93I 

2.064 

14.65 

0.142 

.788 

1.920 

14.11 

0.123 

i-55i 

1.674 

13.72 

4287.566 

0.153 

1.926 

2.059 

14.62 

0.144 

.814 

1.946 

14.30 

O.I22 

I-536 

1.659 

13.60 

4288.310 

0.155 

i-95i 

2.084 

14.80 

0.143 

.800 

1.932 

14.20 

0.124 

1.560 

1.683 

13.80 

4290.377 

0.151 

1.900 

2-033 

14.43 

0.142 

1-785 

1.917 

14.09 

0.123 

J-547 

1.670 

13.69 

4290.542 

0.152 

1.911 

2.044 

M-S1 

0.143 

1.799 

I-93I 

14.19 

O.I22 

1-535 

1.658 

13-59 

4291.630 

0.153 

1.924 

2.057 

14.60 

0.142 

1.785 

1.917 

14.09 

0.125 

i-57i 

1.694 

13.89 

4294.936 

0.152 

1.909 

2.O42 

14.50 

0.144 

i.  808 

1.940 

14.26 

O.I24 

J-555 

1.678 

I3-76 

<t>  =  4Sto 

0  =6o?o 

<t>  =  75!° 

4196.699 

0.089 

1.162 

1.267 

12.72 

0.060 

0.779 

0.86  1 

12.23 

O.O28 

0.366 

0.416 

11.41 

4197.257 

0.088 

1.147 

1.252 

12.57 

0.058 

0-754 

0.836 

11.87 

O.O28 

0.366 

0.416 

11.41 

4203.730 

0.090 

1.172 

1.277 

12.82 

0.060 

0.778 

0.860 

12.21 

0.030 

0.390 

0.440 

12.07 

4209.144 

0.091 

1.182 

.287 

12.92 

0.059 

0.763 

0.845 

12.00 

0.031 

0.400 

0.450 

12.34 

4216.136 

0.088 

1.140 

•245 

12.50 

0.058 

0-751 

0-833 

11.83 

0.030 

0.389 

0-439 

12.04 

4220.509 

0.090 

1.164 

.269 

12.74 

0.060 

0-777 

0.859 

12.  2O 

0.030 

0.389 

0-439 

12.04 

4232.887 

0.091 

1.172 

•277 

12.82 

0.062 

0.800 

0.882 

12-52 

0.032 

0.412 

0.462 

12.67 

4257.815 

0.092 

1.171 

.276 

12.81 

0.066 

0.841 

0.923 

13.11 

0.034 

0.431 

0.481 

13-19 

4258.477 

0.091 

I-I59 

.264 

12.69 

0.062 

0.789 

0.871 

12-37 

0.033 

0.420 

0.470 

12.89 

4265.418 

0.093 

1.181 

.286 

12.91 

0.064 

0.815 

0.897 

12.74 

0-033 

0.420 

0.470 

12.89 

4266.081 

0.094 

1.194 

-299 

13-04 

0.062 

0.787 

0.869 

12.34 

0-033 

0.420 

0.470 

12.89 

4268.915 

0.092 

1.167 

.272 

12-77 

0.062 

0.787 

0.869 

12-34 

0.032 

0-405 

0-455 

12.48 

4276.836 

0.092 

1.164 

.269 

12.74 

0.063 

0.800 

0.882 

12.52 

0.031 

0-394 

0.444 

12.  18 

4284.838 

0.090 

i-i3S 

.240 

12.45 

0.062 

0.782 

0.864 

12-37 

0.031 

0-393 

0-443 

12.15 

4287.566 

0.093 

1.170 

-275 

12.80 

0.065 

0.816 

0.898 

12.75 

0-035 

0.441 

0.491 

13-47 

4288.310 

0.092 

1.158 

.263 

12.68 

0.063 

0.792 

0.874 

12.41 

0.032 

0.404 

0-454 

12.45 

4290.377 

0.094 

1.182 

.287 

12.92 

0.060 

0.762 

0.844 

11.98 

0.032 

0.404 

0.454 

12.45 

4290.542 

0.093 

1.170 

•275 

12.80 

0.062 

0.781 

0.863 

12.25 

0-033 

0.414 

0.464 

12.73 

4291.630 

0.093 

1.169 

1.274 

12.79 

0.066 

0.831 

0.913 

12.96 

0.032 

0.403 

0-453 

12.43 

4294.936 

0.094 

1.179 

1.284 

12.89 

0.064 

0.806 

0.888 

12.61 

0.032 

0.403 

0-453 

12.43 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  u  25.     1906,  June  15,  6h  35™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.3  mm.     Quality,  good. 


P-f 


sec  7) 


O 

o-n 
p 
D 


83-7 

9-3 
9.9 

1.2 


Diameter  169.5  mm 
Factor        i  .030 


15.0 
30.0 

15.0 
30.0 

7S-o 
60.0 

4-5 

2-3 

1.003 
I.OOI 

45-o 
60.0 

45-° 
60.0 

45-o 
30.0 

i-7 
1.4 

1.  000 
I.OOO 

75-Q 

7S-° 

15.0 

1.2 

I.OOO 

90.0 

90.0 

o.o 

1.2 

I.OOO 

#- 

o°o 

0  = 

is!° 

*- 

3°!° 

A 

• 

M-., 

1 

A 

V 

.  +  ., 

f 

A 

V 

,-M, 

£ 

km 

km 

„ 

km 

km 

0 

km 

km 

0 

4196.699 

0.149 

•943 

2.076 

14-74 

0.139 

1.810 

1.942 

14.27 

0.118 

1-537 

1.660 

13.61 

4197-257 

0.150 

•957 

2.090 

14.84 

0.142 

1.847 

1.979 

14-55 

O.I  2O 

•564 

1.687 

13-83 

4203.730 

0.151 

•965 

2.098 

14.89 

0.144 

1.869 

2.OOI 

14.71 

0.118 

-540 

1.663 

13-63 

4209.144 

o.i54 

.989 

2.122 

15.06 

0.144 

1.867 

1.999 

14.69 

0.127 

.651 

1-774 

14-54 

4216.136 

0.146 

.889 

2.022 

14.36 

0.141 

1.823 

1-955 

14-37 

0.116 

.502 

-625 

13-32 

4220.509 

0.150 

•937 

2.070 

14.70 

0.146 

1.887 

2.019 

14.84 

0.125 

.614 

•737 

14.24 

4232-887 

0.151 

•943 

2.076 

14.74 

0.144 

1-853 

1.985 

14-59 

0.120 

-542 

.665 

13-65 

4257-8I5 

0.150 

.911 

2.044 

14-51 

0.145 

1.843 

1-975 

14-52 

0.124 

-576 

.699 

13-93 

4258-477 

O.I5S 

.961 

2.094 

14-87 

0.145 

1-843 

1-975 

14-52 

O.I  2O 

.526 

•649 

13-52 

4265.418 

0.147 

.867 

2.OOO 

14.20 

0.146 

1-854 

1.986 

14.60 

0.125 

.586 

•709 

14.01 

4266.081 

0.151 

.917 

2.O50 

H-55 

0.148 

1.878 

2.010 

14-77 

O.I  20 

-524 

.647 

13-50 

4268.915 

0.152 

.927 

2.060 

14.62 

0.146 

1.851 

1.983 

14-58 

O.I  21 

•530 

•653 

13-55 

4276-836 

0.151 

.909 

2.O42 

14.50 

0.143 

1.  808 

1.940 

14.26 

O.I22 

•  541 

.664 

13-64 

4284.838 

0.154 

.941 

2.074 

14.72 

0.144 

1.818 

1.950 

14-33 

0.122 

-538 

.661 

13.62 

4287.566 

0.154 

•936 

2.069 

14.69 

0.146 

1.839 

1.971 

14.49 

O.II9 

•499 

.622 

13-30 

4288.310 

0-153 

•925 

2.058 

14.61 

0.142 

1-777 

1.909 

14-03 

O.II7 

•474 

•597 

13.09 

4290.377 

0.152 

.911 

2.044 

I4-5I 

0.138 

1.738 

1.870 

13-74 

0.120 

.508 

.631 

13-37 

4290.542 

0-153 

.921 

2.054 

14.58 

0.142 

1.776 

1.908 

14.02 

O.I22 

•533 

.656 

13-58 

4291-630 

0.150 

.888 

2.O2I 

14-35 

0.142 

1.776 

1.908 

14.02 

O.II9 

•497 

.620 

13.28 

4294-936 

0.152 

•909 

2.O42 

14.50 

0-144 

1.808 

1.940 

14.26 

O.I2I 

•517 

.640 

13-44 

*- 

45> 

*- 

6o°o 

,- 

75?° 

4196.699 

0.087 

•135 

1.240 

12.45 

0.054 

0.703 

0.785 

11.15 

0.026 

0.340 

0.390 

10.63 

4197-257 

0.088 

•  147 

1.252 

12.57 

0-059 

0.769 

0.851 

1  2.08 

0.035 

0.442 

0.492 

13-41 

4203.730 

0.086 

.120 

1.225 

12.30 

0.063 

0.819 

0.901 

12.79 

0.032 

0.416 

0.466 

12.70 

4209.144 

0.090 

.169 

1.274 

12-79 

0.066 

0-855 

0-937 

13-30 

0.031 

0.405 

0-455 

12.40 

4216.136 

0.086 

.114 

1.219 

12.24 

0-053 

0.685 

0.767 

10.89 

0.025 

0-324 

0-374 

10.19 

4220.509 

0.096 

.242 

1-347 

I3-S2 

0.058 

0.748 

0.830 

11.79 

0.031 

0.342 

0.392 

10.68 

4232.887 

0.093 

.197 

1.302 

13-07 

0.062 

0.798 

0.880 

12.50 

0.032 

0.411 

0.461 

12.56 

4257-815 

0.092 

.171 

1.276 

12.81 

0.062 

0.790 

0.872 

12.38 

0.034 

0.447 

0-497 

13-54 

4258.477 

0.090 

•145 

1.250 

12-55 

0.060 

0.764 

0.846 

12.01 

O.027 

0-345 

0-395 

10.76 

4265.418 

0.086 

.092 

1.197 

12.  02 

0.064 

0-759 

0.841 

11.94 

0.031 

0-394 

0-444 

12.10 

4266.081 

0.096 

.220 

1-325 

I3-30 

0.06  1 

0.776 

0.858 

12.18 

0.026 

0-331 

0.381 

10.38 

4268.915 

o.ogi 

•155 

1.260 

12.65 

0.065 

0-776 

0.858 

12.18 

0.032 

0.406 

0.456 

12-43 

4276.836 

0.090 

.138 

1-243 

12.48 

0.063 

0.800 

0.882 

12.52 

0.032 

0.406 

0.456 

12.43 

4284.838 

0.095 

•°95 

i.  200 

12.05 

0.068 

0.857 

0-939 

13-33 

0.028 

0-354 

0.404 

II.  OI 

4287.566 

0.092 

.158 

1.263 

12.68 

0.066 

0-832 

0.914 

12.98 

0.030 

0.378 

0.428 

11.66 

4288.310 

0.091 

•H5 

1.250 

12-55 

0.057 

0.717 

0-799 

"•35 

O.O29 

0.364 

0.414 

11.28 

4290.377 

0.096 

.207 

1.312 

13-17 

0.064 

0.807 

0.889 

12.62 

0.037 

0.465 

0.515 

14.04 

4290.542 

0.092 

•157 

1.262 

12.67 

0.062 

0.782 

0.864 

12.27 

O.O28 

0-373 

0.423 

"•53 

4291.630 

0.097 

.219 

1-324 

13.29 

0.059 

0.742 

0.824 

11.70 

O.O29 

0.364 

0.414 

11.28 

4294-936 

0-097 

.217 

1.322 

13.27 

0.064 

0.802 

0.884 

12.55 

0.028 

0-353 

0.403 

10.98 

26    AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OP   THE   SUN   BY   SPECTROSCOPIC   METHODS. 

TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  26.     1906,  June  16,  6'1  20'™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.7  mm.     Quality,  good. 


0      84.5 

iS-o 

15-1 

74-9 

4.9 

1.004 

O-fi      10.1 

30.0 

30.0 

60.0 

2-5 

I.OOI 

P           9-5 

45-0 

4S-o 

45-0 

1.8 

I.OOI 

D           1.3 

60.0 

60.0 

30.0 

i-5 

I.OOO 

Diameter  1  70.0  mm 

7S-o 

7S-° 

15.0 

i-3 

I.OOO 

Factor        1.033 

90.0 

90.0 

o.o 

i-3 

I.OOO 

,- 

o?o 

#- 

is!o 

0  = 

3°!° 

\ 

A 

A 

V 

,  +  ,, 

1 

A 

I 

,  +  ,, 

e 

A 

V 

11  4-  11, 

1 

km 

km 

0 

km 

km 

0 

km 

km 

„ 

4196.699 

0.150 

1.956 

2.089 

14.83 

0.138 

1.804 

1.936 

14.22 

0.114 

1.491 

1.614 

13.22 

4197-257 

0.148 

1.936 

2.069 

14.69 

0.138 

1.803 

1-935 

14.22 

0.115 

1.501 

1.624 

I3-30 

4203.730 

0.148 

I-93I 

2.064 

14.65 

0.144 

1.878 

2.OIO 

14-77 

0.116 

1.509 

1.632 

13-37 

4209.144 

0.152 

1.972 

2.105 

14.94 

0.144 

1.876 

2.008 

14-75 

O.I  2O 

1-558 

I.68I 

13-77 

4216.136 

0.147 

1.910 

2.043 

0-137 

1-777 

1.909 

14.02 

O.II2 

1-455 

1-578 

12.92 

4220.509 

0.147 

1.910 

2.043 

14.50 

0.144 

1.867 

1-999 

14.69 

O.I22 

1.581 

1.704 

13.96 

4232.887 

0.152 

1-963 

2.096 

14.88 

0.144 

1.858 

1.990 

14.62 

O.I2I 

1.562 

1.685 

13.80 

4257-815 

0.159 

2.030 

2.163 

15-36 

0.144 

1.848 

1.980 

14.55 

O.llS 

1.506 

1.629 

13-34 

4258.477 

0.155 

1.978 

2.  Ill 

14.99 

0.147 

1.876 

2.008 

14.75 

O.I  2O 

I-527 

1.650 

I3-5I 

4265.418 

0.152 

1.936 

2.069 

14.69 

O.I4S 

1.848 

1.980 

14.55 

0.123 

1-565 

1.688 

13.82 

4266.081 

0.152 

1-935 

2.068 

14.68 

0.146 

1.858 

1.990 

14.62 

O.llS 

I-503 

1.626 

I3-32 

4268.915 

0.152 

•934 

2.067 

14.67 

0.150 

1.907 

2.039 

14.98 

0.116 

1.476 

1-599 

13.10 

4276.836 

0.151 

.912 

2.045 

14-52 

0.144 

1.823 

1-955 

14.36 

O.I  2O 

1.520 

1.643 

I3-46 

4284.838 

0.154 

-945 

2.078 

14-75 

0.148 

1.867 

1-999 

14.69 

0.116 

1-475 

1.598 

13.09 

4287.566 

0.151 

•907 

2.O4O 

14-48 

0.148 

1.867 

1-999 

14.69 

0.122 

1-538 

i.  66  1 

13.60 

4288.310 

0.150 

.904 

2.037 

14.46 

0.149 

1.  880 

2.OI2 

14.78 

O.II7 

1.481 

1.604 

I3-I4 

4290.37? 

0.155 

•964 

2.097 

14.89 

0.142 

1.790 

1.922 

14.12 

O.llS 

1.491 

1.614 

13.22 

4290.542 

0.154 

•942 

2.075 

14-73 

0.144 

1.815 

1-947 

14-30 

O.I  2O 

1.512 

1-635 

13-39 

4291.630 

0.148 

.868 

2.001 

14.21 

0.146 

1.841 

1-973 

14.49 

O.I2I 

1.522 

1.645 

13-47 

4294.936 

0.157 

1.976 

2.109 

14.97 

0.144 

1.811 

1-943 

14.27 

O.I  2O 

1.510 

1-633 

13-37 

,- 

45?° 

*- 

«*, 

0  = 

74:, 

4196.699 

0.087 

1.136 

1.241 

12.45 

0.060 

0.787 

0.867 

12.27 

0.033 

0-434 

0.484 

I3-I9 

4197-257 

0.086 

.126 

1.231 

12.35 

0.058 

0.761 

0.841 

11.91 

0.030 

0-393 

0-443 

12.07 

4203.730 

0.088 

•145 

1.250 

12.54 

0.06  1 

0.796 

0.876 

12.40 

0.031 

0.407 

0-457 

12.45 

4209.144 

0.093 

.206 

1.311 

13-14 

0.060 

0.782 

0.862 

12.  2O 

0.036 

0.469 

0-519 

14.14 

4216.136 

0.088 

.142 

1.247 

12.51 

0.065 

0.846 

0.926 

13.11 

0.030 

0.391 

0.441 

I2.O2 

4220.509 

0.093 

•  203 

1.308 

13.12 

0.06  1 

0-793 

0.873 

12.36 

0.030 

0.390 

0.440 

"•99 

4232.887 

0.090 

.160 

1.265 

12.69 

0.062 

0.801 

0.881 

12.47 

0.034 

0.438 

0.488 

I3-30 

4257-815 

0.090 

1.150 

1-255 

12.59 

0.054 

0.732 

0.812 

11.49 

0.030 

0-383 

0-433 

11.80 

4258-477 

0.092 

1.174 

1.279 

12.83 

0.065 

0.830 

0.913 

12.92 

0-035 

0-445 

0.495 

13-49 

4265.418 

0.090 

1.148 

1-253 

12-57 

0.059 

o-753 

0-833 

11.79 

0.030 

0.382 

0-432 

11.77 

4266.081 

0.095 

1.209 

1-314 

13.18 

0.063 

0.803 

0.883 

12.50 

0.032 

0.409 

0-459 

12.51 

4268.915 

0.094 

1.197 

1.302 

13.06 

0.060 

0.763 

0.843 

"•93 

0.035 

0.444 

0-494 

13.46 

4276.836 

0.092 

1.166 

1.271 

12.75 

0.063 

0.801 

0.881 

12.47 

0.028 

0.382 

0.432 

11.77 

4284.838 

0.092 

1.163 

1.268 

12.72 

0.057 

0.716 

0.796 

11.27 

0.034 

0.431 

0.481 

13.11 

4287.566 

0.093 

1-173 

1.278 

12.82 

0.068 

0.860 

0.940 

13-31 

0.034 

0.431 

0.481 

13.11 

4288.310 

0.095 

1.199 

1.304 

13.08 

0.06  1 

0.770 

0.850 

12.03 

0.030 

0.380 

0.430 

11.72 

4290.377 

0.092 

1.159 

1.264 

12.68 

0.06  1 

0.769 

0.849 

12.  02 

0.032 

0.406 

0.456 

12-43 

4290.542 

0.094 

1.183 

1.288 

12.92 

0-057 

0.719 

0-799 

11.31 

0.031 

0-391 

0.441 

12.  02 

4291.630 

0.094 

1.183 

1.288 

12.92 

0.058 

0-733 

0.813 

11.51 

O.O28 

0-355 

0.405 

II.O4 

4294.936 

0.096 

1.207 

1.312 

13.16 

0.064 

0.804 

0.884 

12.51 

0.030 

0-379 

0.429 

11.69 

RESULTS    FOR    INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907 — -Continued. 
Plate  »  27.     1906,  June  16,  7h  sra  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.7  mm.     Quality,  good. 


t-P 


SCOT 


o 

84.6 

15.0 

iS-i 

74-9 

4-9 

1.004 

o-n 

10.2 

30.0 

30.0 

60.0 

2-5 

I.OOI 

p 

9-5 

4S-o 

45-° 

45-° 

1.8 

I.OOI 

D 

i-3 

60.0 

60.0 

30.0 

i-5 

I.OOO 

Diameter 

170.0  mm 

7S-o 

75-o 

15-0 

i-3 

I.OOO 

Factor 

i-°33 

90.0 

90.0 

o.o 

i-3 

I.OOO 

•t>  - 

0°O 

0  = 

ig'o 

<*>  = 

3°!° 

A 

V 

•0  +  II, 

£ 

A 

V 

v  +  VL 

f. 

A 

V 

»  +  *'[ 

1 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.152 

1.990 

2.123 

15-07 

0.136 

1-779 

1.911 

14.04 

0.114 

.491 

1.614 

13-23 

4I97-2S7 

0.146 

1.909 

2.O42 

14-50 

0.134 

-753 

1.885 

13-85 

0.116 

.516 

1.639 

13-44 

4203.730 

0.146 

1.906 

2.039 

14.48 

0.137 

•785 

.917 

14.09 

0.119 

•552 

I-675 

13.73 

4209.144 

0.148 

1.928 

2.o6l 

14.63 

0.142 

-851 

•983 

14.58 

0.122 

-584 

1.707 

13-99 

4216.136 

0.150 

1.949 

2.082 

14.78 

0.138 

.791 

•923 

14.13 

0.116 

.510 

1.623 

13-31 

4220.509 

0.152 

1.972 

2.105 

14.94 

0.145 

.879 

.on 

14.78 

0.126 

-633 

I-756 

14.40 

4232.887 

0.150 

1-937 

2.070 

14.70 

0.142 

-834 

.966 

14-45 

O.I2I 

•555 

1.678 

13.76 

42S7-8iS 

0.153 

1-953 

2.086 

14.81 

0.146 

.866 

.998 

14.69 

0.126 

.604 

1.727 

14.16 

4258.477 

0.152 

1.941 

2.074 

14.72 

0.145 

.851 

1.983 

14.58 

0.119 

•5i7 

1.640 

13-44 

4265.418 

0.148 

1.885 

2.0l8 

14-33 

0.141 

•793 

1-925 

14.15 

O.I22 

•553 

1.676 

13-74 

4266.081 

0.148 

1.885 

2.018 

14-33 

0.141 

.792 

1.924 

14.14 

0.122 

-553 

1.676 

13-74 

4268.915 

0.153 

1-947 

2.o8o 

14-77 

0.149 

-893 

2.025 

14.88 

0.123 

-563 

1.686 

13.82 

4276.836 

0.146 

1.852 

1.985 

14.09 

0.142 

•799 

1.932 

14.20 

O.II9 

.510 

1-633 

13-39 

4284.838 

0.148 

1.872 

2.005 

14.23 

0.145 

-833 

1.965 

14.44 

O.IlS 

•490 

1.613 

13.22 

4287.566 

0.151 

1.906 

2.039 

14.48 

0.147 

-856 

1.988 

14.61 

O.II7 

•478 

i.  60  1 

13.12 

4288.310 

0.151 

1.906 

2.039 

14.48 

0.142 

.790 

1.922 

14-13 

O.I24 

.564 

1.687 

13-83 

4290.377 

0.151 

1.905 

2.038 

14.47 

0.141 

.780 

1.912 

14.05 

O.II8 

1.488 

1.611 

13.21 

4290.542 

0.159 

2.005 

2.138 

15.18 

0.148 

•865 

1.997 

14.68 

0.120 

1.509 

1.632 

13.38 

4291.630 

0.161 

2.029 

2.162 

15-35 

0.142 

.790 

1.922 

14.13 

O.I  21 

1.522 

1.645 

13.49 

4294.936 

0.156 

1.963 

2.096 

14.88 

0.147 

.850 

1.982 

14-57 

O.I  2O 

1-507 

1.630 

13-36 

#- 

45?o 

<t"= 

6o°o 

<*>  = 

74?9 

4196.699 

0.084 

1.092 

1.197 

I2.O2 

0.056 

0-739 

0.819 

11.63 

0.032 

0.432 

0.482 

13.14 

4197.257 

0.088 

I-I53 

1.258 

12.63 

0.059 

0.772 

0.852 

12.10 

O.O29 

0-394 

0.444 

12.  IO 

4203.730 

0.082 

1.069 

1.174 

11.79 

0.060 

0.782 

0.862 

12.24 

0.034 

0-457 

0.507 

13.82 

4209.144 

0.095 

1.238 

1.338 

13-43 

0.060 

0.778 

0.858 

12.  l8 

0.030 

0.404 

0-454 

12.37 

4216.136 

0.086 

1.118 

1.223 

12.28 

0.06  1 

0.794 

0.874 

12.41 

0.032 

0.430 

0.480 

13.08 

4220.509 

0.092 

1.190 

1.295 

13.00 

0.058 

0.752 

0.834 

11.84 

O.O29 

0-392 

0.442 

12.05 

4232.887 

0.094 

i.  216 

1.321 

13.26 

0.056 

0.706 

0.786 

ii.  16 

O.O28 

0-375 

0.425 

11.58 

4257-815 

0.092 

1.176 

1.281 

12.86 

0.059 

0.749 

0.829 

11.77 

O.026 

0-343 

0-393 

10.71 

4258.477 

0.092 

1.174 

1.279 

12.84 

0.060 

0.768 

0.848 

12.04 

0.034 

0.449 

0.499 

13.60 

4265.418 

0.093 

1.185 

1.290 

12.95 

0.06  1 

0.778 

0.858 

12.  l8 

0.034 

0.448 

0.498 

13-57 

4266.081 

0.096 

i.  220 

I-325 

13-30 

0.058 

0-737 

0.817 

1  1.  60 

0-035 

0.462 

0.512 

13-95 

4268.915 

0.092 

1.169 

1.274 

12.79 

0.060 

0.758 

0.838 

11.90 

0.028 

0.369 

0.419 

11.42 

4276.836 

0.096 

i.  218 

I.323 

13-28 

0.058 

0.736 

0.816 

"•59 

O.O28 

0.369 

0.419 

11.42 

4284.838 

0.096 

i.  216 

1.321 

13.26 

0.058 

0-734 

0.814 

11.56 

0.032 

0.427 

0.47.7 

13.00 

4287.566 

0.088 

1.114 

1.219 

12.24 

0.056 

0.705 

0.783 

11.15 

0.031 

0.408 

0.458 

12.48 

4288.310 

0.084 

1.062 

1.167 

11.72 

0.060 

0.751 

0.831 

11.80 

0.030 

0-393 

0.443 

12.07 

4290.377 

0.093 

1.174 

1.279 

12.84 

0.046 

0.685 

0.765 

10.86 

0.031 

0.408 

0.458 

12.48 

4290.542 

0.096 

1.  211 

1.316 

13.21 

0.048 

0.730 

0.810 

11.50 

0.037 

0.483 

0-533 

14-53 

4291.630 

0.091 

I.I48 

1-253 

12.58 

0.059 

0-743 

0.823 

11.69 

0.033 

0-433 

0.483 

13.16 

4294.936 

0.093 

I-I73 

1.278 

12.83 

0.058 

0-733 

0.813 

"•54 

0.036 

0.470 

0.520 

14.17 

28     AN   INVESTIGATION   OF    THE   ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1906-1907 — -Continued. 
Plate  <«>  30.     1906,  Oct.  19,  nh  iom  G.  M.  T.     Measured  by  A.  on  G.     Distance  from  Limb  3.6  mm.     Quality,  good. 


P-f 

7T 

t> 

T\ 

sec') 

0 

a 
205.6 

O 

14.9 

I5'.8 

74.2 

2O.4 

1.067 

o-o 

I3I.2 

29.9 

3°-3 

59-7 

10.8 

1.018 

p    -26.2 

44-9 

45-2 

44.8 

7-7 

1.009 

D 

5-4 

59-9 

60.0 

30.0 

6-3 

1.  006 

Diameter 

171.9  mm 

74-9 

75-° 

15.0 

S.6 

1.  005 

Factor 

1.044 

89.9 

89.9 

O.I 

5-4 

1.005 

<t>  = 

0°I 

*- 

is!o 

0  = 

3°!° 

A 

H 

11  +  1!l 

« 

A 

V 

11+  Dj 

f 

A 

D 

»+  »! 

£ 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.148 

1.967 

2.106 

14.95 

0.136 

1.  808 

1-947 

14-31 

0.114 

.516 

1.642 

13.46 

4I97-257 

0.148 

1.966 

2.105 

14.94 

0.136 

1.807 

1.946 

14.30 

O.I  I  2 

-489 

1.615 

13-24 

4203.730 

0.148 

1.962 

2.IOI 

14.92 

0.138 

1.830 

1.969 

14.47 

0.116 

•540 

1.666 

13.66 

4209.144 

0.148 

1.958 

2.097 

14.89 

0.136 

1-799 

1.938 

14.24 

0.116 

•537 

1.663 

13-63 

4216.136 

0.146 

1.926 

2.065 

14.66 

0-135 

1.781 

1.920 

14.11 

0.113 

.492 

1.618 

13.26 

4220.509 

0.148 

J-949 

2.088 

14.82 

0.138 

1.817 

1.956 

14-38 

0.118 

•555 

1.681 

13-78 

4232.887 

0.150 

1.966 

2.105 

14.94 

0.137 

.796 

1-935 

14.22 

0.118 

•548 

1.674 

13-72 

4257-8I5 

0.150 

1.946 

2.085 

14.80 

0-139 

.803 

1.942 

14.27 

0.120 

•558 

1.684 

13.80 

4258.477 

0.149 

1-933 

2.072 

14.71 

0.138 

•790 

1.929 

14.18 

O.II9 

1-545 

i.  66  1 

13.62 

4265.418 

0.150 

1.941 

2.o8o 

14-77 

0.138 

.786 

1.925 

14-15 

O.II8 

1.528 

1.654 

13-56 

4266.081 

0.150 

1.941 

2.080 

14-77 

0.138 

.786 

1-925 

14-15 

O.IlS 

1.528 

1.654 

13-56 

4268.915 

0.152 

1.964 

2.103 

14-93 

0.140 

.809 

1.948 

14.32 

O.IlS 

-526 

1.652 

13-54 

4276.836 

0.148 

1.905 

2.044 

14-51 

0.138 

•  777 

1.916 

14.08 

0.116 

.496 

1.622 

13-30 

4284.838 

0.150 

I-925 

2.064 

14.65 

0.139 

•785 

1.924 

14.14 

0.118 

.516 

1.642 

13.46 

4287.566 

0.152 

1.949 

2.088 

14.82 

0.139 

.782 

1.921 

14.12 

0.117 

.502 

1.628 

13-35 

4288.310 

0.150 

I-923 

2.O62 

14.64 

0.138 

.769 

1.908 

14.02 

0.118 

•514 

1.640 

13-44 

4290.377 

0.148 

1.896 

2-035 

14-45 

0.140 

•793 

1.932 

14.20 

0.116 

.487 

1.613 

13.22 

4290.542 

0.148 

1.896 

2-035 

14-45 

0.139 

.780 

1.919 

14.10 

0.118 

•513 

1.639 

13-44 

4291.630 

0.149 

1.907 

2.046 

14-52 

0.140 

•793 

1.932 

14.20 

0.118 

•512 

1.638 

13.43 

4294.936 

0.148 

1.892 

2.031 

14.42 

0.144 

.841 

1.980 

14-55 

0.118 

.510 

1.636 

13-41 

<t>  = 

44!» 

<t>  = 

S9?7 

4,  = 

74?2 

4196.699 

0.090 

.201 

1.308 

13.08 

0-057 

0.767 

0.847 

11.92 

O.O22 

0.311 

0.358 

9-33 

4I97-2S7 

0.090 

.2OI 

1.308 

13.08 

0.054 

0.713 

0-793 

ii.  16 

0.026 

0.372 

0.419 

10.93 

4203.730 

0.093 

.238 

1-345 

13-45 

0.056 

0.752 

0.832 

11.71 

0.028 

0.400 

0.447 

11.66 

4209.144 

0.092 

.222 

1.329 

13.29 

0.058 

0.777 

0.857 

12.06 

0.023 

0-321 

0.368 

9.60 

4216.136 

0.089 

.179 

.286 

12.86 

0.056 

0.750 

0.830 

11.68 

0.024 

0.342 

0.389 

10.14 

4220.509 

0.092 

.217 

•324 

13.24 

0.058 

0-774 

0.854 

12.02 

0.026 

0-357 

0.404 

11.32 

4232.887 

0.091 

.198 

•305 

13-05 

0.058 

0.770 

0.850 

11-97 

O.O26 

0.364 

0.411 

10.72 

4257-815 

0.090 

-173 

.280 

12.80 

0.060 

0.789 

0.869 

12.23 

O.O28 

0.391 

0.438 

11.42 

4258.477 

0.092 

.199 

-306 

13.06 

0.059 

0.776 

0.856 

12.05 

0.028 

0.385 

0.432 

11.26 

4265.418 

0.094 

.221 

-328 

13.28 

0.060 

0.787 

0.867 

12.20 

0.028 

0.387 

0-434 

11.32 

4266.081 

0.096 

1.247 

•354 

13-54 

0.060 

0.787 

0.867 

12.  2O 

0.028 

0.389 

0.436 

n-37 

4268.915 

0.096 

1-245 

-352 

13-52 

0.059 

0-773 

0-853 

12.  OI 

O.O26 

0-354 

0.401 

10.46 

4276.836 

0.093 

1.203 

.310 

13.10 

0.058 

0.756 

0.836 

11.77 

O.O27 

o.374 

0.421 

10.98 

4284-838 

0.096 

1.238 

•345 

13-45 

0.058 

0-754 

0.834 

11-74 

0.026 

0.348 

0-395 

10.30 

4287.566 

0.095 

1.223 

•330 

13-30 

0.058 

0-753 

0.833 

"•73 

0.030 

0.403 

0.450 

n-73 

4288.310 

0.094 

1.  211 

-318 

13.18 

0.059 

0.766 

0.846 

n.  91 

O.O26 

0.348 

0-395 

10.30 

4290-377 

0.096 

1-235 

•342 

13-42 

0.058 

0.752 

0.832 

11.71 

O.O27 

0.362 

0.409 

10.66 

4290.542 

0.097 

1.247 

•354 

13-54 

0.058 

0.752 

0.832 

11.71 

0.030 

0.413 

0.460 

11.99 

4291.630 

0.096 

1-235 

-342 

13-42 

0.058 

0-752 

0.832 

11.71 

O.O28 

0.386 

0-433 

11.29 

4294.936 

0.097 

1-245 

•352 

13-52 

0.060 

0.777 

0.857 

12.06 

O.O27 

0.364 

0.411 

10.72 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


TABLE  4.  —  RESULTS  FOR_!NDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Platew3i.     1906,  Oct.  19,  i2h  iom  G.  M.  T.    Measured  by  A.  on  G.    Distance  from  Limb  3.6  mm.    Quality,  good. 


P-P 


seci 


0 

205 

7 

14.9 

15.8 

74.2 

20.4 

1.067 

G-!2 

131 

3 

29.9 

3°-3 

59-7 

10.8 

1.018 

P      -26.2 

44-9 

45-2 

44.8 

7-7 

1.009 

D 

5 

4 

59-9 

60.0 

30.0 

6.3 

i.  006 

Diameter 

171 

9  mm 

74-9 

7S-0 

15.0 

S-6 

1.005 

Factor 

i 

.044 

89.9 

89.9 

O.I 

S-4 

1.005 

0  = 

O°I 

0  = 

15!° 

0  = 

3°!° 

A 

V 

»  +  «, 

{ 

A 

s 

»  +  r, 

1 

A 

D 

t)  +  Dj 

• 

km 

km 

0 

km 

km 

0 

km 

km 

. 

4196.699 

0.148 

1.967 

2.106 

14-95 

0.138 

.834 

1.972 

14.49 

O.I  l6 

•544 

.670 

13.69 

4I97-257 

0.147 

1-954 

2.093 

14.86 

0.138 

-834 

1.972 

14.49 

0.118 

•569 

.695 

13.90 

4203.730 

0.149 

1.976 

2.115 

15.02 

0.140 

-856 

1.994 

14.66 

0.119 

.580 

.706 

13.98 

4209.144 

0.150 

1.985 

2.124 

15.08 

0.140 

.852 

1.990 

14.63 

O.I  2O 

.589 

•715 

14.06 

4216.136 

0.147 

1.940 

2.079 

14.76 

0.138 

.820 

1.958 

14-39 

0.118 

•559 

•685 

13.81 

4220.509 

0.150 

1.976 

2.115 

15.02 

0.140 

•844 

1.982 

14-57 

0.118 

-556 

.682 

13-79 

4232.887 

0.149 

1-954 

2.093 

14.86 

0.140 

.835 

1-973 

14.50 

O.I  2O 

•574 

.700 

13-94 

4257.8IS 

0.150 

1.946 

2.085 

14.80 

0.143 

.855 

t-993 

14-65 

O.I  2O 

•559 

-685 

13.81 

4258.47? 

0.150 

1.946 

2-085 

14.80 

0.140 

.816 

1-954 

14-36 

O.I  2O 

•559 

•685 

13.81 

4265.418 

0.150 

1.941 

2.080 

14-77 

0.142 

.837 

1-975 

14-52 

0.120 

•555 

.681 

I3-78 

4266.081 

0.150 

1.941 

2.080 

14.77 

0.141 

.824 

1.962 

14.42 

O.I  21 

-567 

.693 

13.88 

4268.915 

0.150 

1.938 

2.077 

14.74 

0.141 

.821 

1-959 

14.40 

O.I  2O 

•552 

.678 

13-76 

4276.836 

0.151 

1-945 

2.084 

14.80 

0.141 

.816 

1-954 

14-36 

0.120 

•547 

-673 

13-71 

4284.838 

0.151 

1.938 

2.077 

14.74 

0.142 

.822 

1.960 

14.41 

O.IlS 

.516 

.642 

13.46 

4287.566 

0.150 

1.924 

2.063 

14-65 

0.140 

.796 

1-934 

14.21 

O.IlS 

•515 

.641 

13-45 

4288.310 

0.148 

1.898 

2.037 

14.46 

0.142 

.820 

1.958 

14-39 

O.I  2O 

•540 

.666 

13.66 

4290.377 

0.148 

1.896 

2-°3S 

14.45 

0.140 

•793 

I-93I 

14.19 

O.II9 

.526 

.652 

'3-54 

4290.542 

0.149 

1.908 

2.047 

14.53 

0.141 

.807 

1-945 

14-30 

0.  122 

•565 

.691 

13.86 

4291.630 

0.150 

1.921 

2.060 

14.62 

0.140 

•793 

I-93I 

14.19 

O.I  2O 

•539 

-665 

13-65 

4294.936 

0.150 

1.918 

2.057 

14.60 

0.140 

.790 

1.928 

14.17 

0.120 

-536 

.662 

13.62 

0  = 

44?8 

<*>  = 

S9t7 

0  = 

74?2 

4196.699 

0.090 

I.2OI 

1.308 

13-08 

0.058 

0.781 

0.86  1 

12.12 

O.027 

0.381 

0.428 

ii.  16 

4I97-257 

0.088 

I-I73 

1.280 

1  2.80 

0.060 

0.808 

0.888 

12.50 

0.030 

0.423 

0.470 

12.25 

4203.730 

0.090 

1.198 

•305 

13.05 

0.060 

0.806 

0.886 

12-47 

0.030 

0.422 

0.469 

12.23 

4209.144 

0.089 

I.I82 

.289 

12.89 

0.060 

0.806 

0.886 

12-47 

0.034 

0-477 

0-524 

13-66 

4216.136 

0.089 

I.I79 

.286 

12.86 

0.059 

0.789 

0.869 

12.23 

O.O28 

0.392 

0-439 

n-45 

4220.509 

0.090 

I.I90 

•297 

12.97 

0.058 

0-774 

0.854 

I  2.  02 

0.031 

0-433 

0.480 

12.52 

4232.887 

0.088 

I-I59 

.266 

12.66 

0.061 

0.810 

0.800 

12.52 

0.028 

0.390 

0-437 

n-39 

4257-815 

0.091 

1.185 

.292 

12.92 

0.06  1 

0.802 

0.882 

12.41 

0-033 

0.454 

0.501 

13.06 

4258-47? 

0.090 

I.I72 

•279 

12.79 

0.062 

0.815 

0.895 

12-59 

0.030 

0.413 

0.460 

11.99 

4265.418 

0.088 

I-I43 

.250 

12.50 

0.060 

0.787 

0.867 

12.  2O 

0.028 

0.384 

0-431 

11.24 

4266.081 

o.ooo 

1.169 

.276 

12.76 

0.059 

0-773 

0-853 

I2.OO 

0.030 

0.412 

0-459 

11.97 

4268.915 

0.091 

1.181 

.288 

12.88 

0.060 

0.786 

0.866 

12.19 

0.030 

0.411 

0.458 

11.94 

4276.836 

o.ooo 

1.164 

.271 

12.71 

0.060 

0.784 

0.864 

12.16 

0.026 

0-356 

0.403 

10.51 

4284.838 

0.089 

1.147 

•254 

12.54 

0.060 

0.781 

0.86  1 

12.12 

0.030 

0.409 

0.456 

11.89 

4287.566 

0.090 

I.I59 

.266 

12.66 

0.060 

0.781 

0.861 

12.12 

O.O27 

0.367 

0.414 

10.79 

4288.310 

0.090 

I-I59 

.266 

12.66 

0.060 

0.780 

0.860 

12.  IO 

0.030 

0.409 

0.456 

11.89 

4290.377 

0.088 

1.131 

-238 

12.38 

0.060 

0.780 

0.860 

12.  IO 

0.028 

0.381 

0.428 

ii.  16 

4290.542 

0.089 

I-I45 

-252 

12.52 

0.059 

0.765 

0.845 

11.89 

0.030 

0.408 

0-455 

11.86 

4291.630 

0.089 

1.144 

•251 

12.51 

0.059 

0.765 

0.845 

11.89 

O.O28 

0.381 

0.428 

ii.  16 

4294.936 

0.090 

I-I55 

.262 

12.62 

o.ooo 

0.778 

0.858 

12.07 

0.027 

0.366 

0-413 

10.77 

The  results  for  Plate  w  35  are  given  on  page  34. 


30     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOP1C   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Platew36.     1906,  Nov.  ii,  ioh  I5m  G.  M.  T.     Measured  by  A.  on  G.     Distance  from  Limb  2.2  mm.     Quality,  good. 


P-P 


secy 


Q 

228.6 

iS-5 

15-8 

74-2 

12.6 

I.O2I 

0-0 

154-2 

3°-S 

3°-7 

59-3 

6.2 

1.  006 

P        -22.6 

45-5 

45-4 

44.6 

4.6 

1.003 

D 

3-i 

60.5 

60.6 

29.4 

3.6 

I.OO2 

Diameter 

171.6  mm 

75-5 

75-5 

14-5 

3-2 

1.002 

Factor 

1.027 

9°-5 

90.5 

-0-5 

3.1 

1.002 

0  = 

-o?5 

0  = 

Ml* 

0  = 

*0°A 

_ 

A 

V 

.  +  ,, 

i. 

A 

V 

V  +  Dj 

1 

A 

V 

H-,, 

1 

km 

km 

0 

km 

km 

. 

km 

km 

a 

4196.699 

0.148 

1.929 

2.670 

14.70 

0.143 

1.865 

2.005 

14.70 

0.119 

•552 

1.682 

13.69 

4197-257 

0.150 

1-955 

2.096 

14.88 

0-143 

1.864 

2.004 

14.69 

0.119 

•551 

1.681 

13.69 

4203.730 

0.151 

•963 

2.104 

14.94 

0.141 

1.834 

1.974 

14-47 

O.I  2O 

.560 

1.690 

13-76 

4209.144 

0.152 

•973 

2.114 

15.01 

0-145 

I.88I 

2.O2I 

14.81 

O.I22 

.583 

1-713 

13-95 

4216.136 

0.151 

•954 

2-095 

14.87 

0.144 

1.864 

2.004 

14.69 

0.120 

•553 

1-683 

13.70 

4220.509 

0.151 

•951 

2.092 

14-85 

0-145 

1-873 

2.OI3 

14-75 

O.I2I 

-563 

1-693 

13-78 

4232.887 

0.151 

.942 

2.083 

14.79 

O.I4S 

1.865 

2.005 

14.70 

O.I  22 

•568 

1.698 

13.82 

42S7.8I5 

0.151 

.921 

2.062 

14.64 

0.145 

1.845 

1.985 

14-55 

0.123 

-565 

1.695 

13.80 

4258.477 

0.153 

•947 

2.088 

14.82 

0.145 

I.845 

1.985 

14-55 

O.I2I 

•539 

1.669 

13-59 

4265.418 

0.152 

.928 

2.069 

14.69 

0.144 

1.828 

1.968 

14.42 

O.I22 

•548 

1.678 

13-66 

4266.081 

0.152 

.928 

2.069 

14.69 

0.145 

1.840 

1.980 

14-51 

O.I  2O 

•523 

1-653 

13.46 

4268.915 

0.152 

.926 

2.067 

14.67 

0.144 

1.825 

1.965 

14.40 

O.I2I 

•533 

1.663 

13-54 

4276.836 

0.151 

.908 

2.049 

14-55 

0.146 

1.844 

1.984 

14-54 

O.I2I 

-528 

1.658 

13-5° 

4284.838 

0.152 

.914 

2.055 

14-59 

0.145 

1.826 

1.966 

14.41 

O.I  2O 

-5" 

1.641 

13-36 

4287.566 

0.151 

.900 

2.041 

14.49 

0.143 

1-799 

1-939 

14.21 

O.I2I 

.522 

1.652 

13-45 

4288.310 

0.151 

.899 

2.040 

14.48 

0.144 

1.811 

I-95I 

14.30 

O.I2I 

.522 

1.652 

13-45 

4290.377 

0.152 

.910 

2.051 

14.56 

0-145 

1.821 

1.961 

14-37 

O.I  20 

.508 

1.638 

13-34 

4290.542 

0.151 

1.898 

2.039 

14.48 

0-145 

1.821 

1.961 

14-37 

O.I2I 

1.520 

1.650 

1.3-43 

4291-630 

0.150 

1.884 

2.025 

14.38 

0.145 

1.821 

1.961 

14-37 

0.122 

1-532 

1.662 

13-53 

4294-936 

0.150 

i.  88  1 

2.022 

14-36 

0.145 

1.819 

J-959 

14.36 

0.122 

1.529 

1.659 

13-51 

0  = 

4* 

0  = 

s*- 

0  = 

^ 

4196.699 

0.089 

1.162 

•273 

12.69 

0.057 

0.746 

0.831 

11.56 

O.O28 

0.372 

0.425 

11.08 

4197-257 

0.089 

1.161 

.272 

12.68 

0.058 

0-758 

0.843 

11.72 

0.030 

0.398 

0.451 

11.76 

4203.730 

0.090 

1.171 

.282 

12.78 

0.058 

0-757 

0.842 

11.71 

0.030 

0.380 

0-433 

11.29 

4209.144 

0.089 

I-I55 

.266 

12.62 

0.060 

0.782 

0.867 

12.  06 

0.030 

0.396 

0-449 

11.71 

4216.136 

0.089 

1.152 

.263 

12.59 

0.057 

0.741 

0.826 

11.49 

O.O29 

0.382 

0-435 

"•34 

4220.509 

0.089 

.150 

.261 

12-57 

0.060 

0.778 

0.863 

I2.OO 

0.030 

0-395 

0.448 

11.68 

4232.887 

0.089 

•145 

.256 

12.52 

0.059 

0.761 

0.846 

11.76 

0.031 

0.406 

0-459 

11.97 

4257-815 

0.090 

.146 

•257 

12-53 

0.062 

0.792 

0.877 

12.  2O 

0.032 

0.415 

0.468 

12.17 

4258.477 

0.090 

.146 

•257 

12.53 

0.06  1 

0.779 

0.864 

12.  OI 

0.031 

0.401 

0-454 

11.84 

4265.418 

0.089 

.130 

.241 

12.37 

0.060 

0.764 

0.869 

I  2.  08 

0.033 

0.427 

0.480 

12.52 

4266.081 

0.090 

•143 

•254 

12.50 

0.060 

0.764 

0.849 

II.8I 

0.032 

0.413 

0.466 

12.15 

4268.915 

0.089 

.129 

.240 

12.36 

0.059 

0.750 

0.835 

ii.  61 

0.032 

0.413 

0.466 

12.15 

4276.836 

0.091 

•151 

.262 

12.58 

0.062 

0.786 

0.871 

12.  II 

O.O29 

0-373 

0.426 

ii.  ii 

4284.838 

0.090 

•'34 

•245 

12.41 

0.060 

0.758 

0.833 

11.58 

0.031 

0-397 

0.450 

"•73 

4287.566 

0.090 

•133 

•244 

12.40 

0.06  1 

0.770 

0.855 

11.89 

0.029 

0-371 

0.424 

1  1.  06 

4288.310 

0.089 

1.  121 

•232 

12.28 

0.061 

0.769 

0.854 

11.88 

0.032 

0.410 

0.463 

12.07 

4290.377 

0.090 

I.I32 

•243 

12.39 

0.059 

0.744 

0.829 

"•S3 

0.031 

0.396 

0-449 

11.71 

4290.542 

0.090 

I.I32 

•243 

12.39 

0.060 

0-757 

0.842 

11.71 

0.030 

0.383 

0.436 

n-37 

4291.630 

0.088 

1.106 

.217 

12.13 

0.062 

0.782 

0.867 

12.06 

0.032 

0.409 

0.462 

12.05 

4294-936 

0.09  1 

1.142 

-253 

12.49 

0.060 

0-755 

0.840 

11.68 

0-033 

0.422 

0-475 

12.39 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1906-1907. 


TABLE  4. —  RESULTS  JOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  37.     1906,  Nov.  n,  ioh  40™  G.  M.  T.     Measured  by  A.  on  G.     Distance  from  Limb  2.2mm.    Quality,  good. 


f-P 


sec  11 


0 

228.6 

iS-7 

16.0 

74.0 

"•5 

I.O2I 

Q-a 

IS4-2 

3°-7 

30.8 

59-2 

6.2 

I.  OO6 

P        -22.6 

45-7 

45.8 

44.2 

4-4 

1.003 

D 

3-i 

60.7 

60.7 

29-3 

3-6 

I.OO2 

Diameter 

171.6  mm 

75-7 

7S-7 

14-3 

3-2 

I.OO2 

Factor 

1.027 

90.7 

90.7 

-0.7 

3-1 

1.002 

<t>  =  -  °!? 

0  =  I4!s 

<t>  =  29°3 

X 

A 

t) 

»  +  », 

i. 

A 

V 

»+»! 

£ 

A 

V 

•  •ft, 

{ 

km 

km 

o 

km 

km 

0 

km 

km 

» 

4196.699 

0.150 

1.960 

2.IOI 

14.92 

0-143 

1.867 

2.007 

14.71 

O.I  2O 

•569 

1.699 

13.84 

4I97-2S7 

0.149 

1.942 

2.083 

14-79 

0.142 

1.850 

1.990 

14-59 

O.I2I 

•574 

1.704 

13.88 

4203.730 

0.149 

•943 

2.084 

14.80 

0.142 

1.849 

1.929 

14.58 

[0.122 

.581 

1.711 

13-94 

4209.144 

0.15-' 

.968 

2.II9 

15-04 

0.142 

1-843 

1-973 

14.46 

O.I22 

-578 

1.708 

13.92 

4216.136 

0.150 

•936 

2.077 

14-75 

0.142 

1-833 

1-973 

14.46 

O.I22 

•584 

1.714 

13-97 

4220.509 

0.151 

•953 

2.094 

14.87 

0.142 

I-835 

1-975 

14.48 

0.  122 

•571 

1.701 

13.86 

4232.887 

°-i54 

.980 

2.  121 

15.06 

0.143 

1.839 

1.979 

14.51 

0.122 

•571 

1.701 

13.86 

4257.815 

0.152 

•934 

2.075 

14-73 

0-143 

1.814 

1-954 

14.32 

O.I22 

•552 

1.682 

13-71 

4258.477 

0.152 

•930 

2.071 

14.70 

0.143 

1.817 

1-957 

14.34 

O.I22 

-557 

1.687 

13-75 

4265.418 

0.150 

.908 

2.049 

14-55 

0.143 

1.812 

1-952 

14.3! 

0.122 

.548 

1.678 

13-67 

4266.081 

0.153 

•937 

2.078 

14-75 

0.143 

1.812 

1-952 

14.31 

O.I  22 

-548 

1.678 

13.67 

4268.915 

0.153 

.942 

2.083 

14-79 

0.143 

1.815 

1-955 

14-33 

O.I  22 

.546 

1.676 

13.66 

4276.836 

0.152 

.926 

2.067 

14.67 

0.143 

1.  806 

1.946 

14.26 

0.123 

•554 

1.684 

13-72 

4284.838 

0.152 

•909 

2.O5O 

14-55 

0.144 

1.810 

1.950 

14.29 

0.123 

•556 

1.686 

13-74 

4287.566 

0-153 

•930 

2.071 

14.70 

0.143 

t-799 

1-939 

14.21 

0.123 

-543 

1-673 

13-63 

4288.310 

0.152 

.916 

2.057 

14.60 

0.143 

1.798 

1.938 

14.20 

0.123 

-545 

I.675 

13-65 

4290.377 

0.151 

•903 

2.044 

14-51 

0.143 

1.799 

1-939 

14.21 

0.123 

•543 

1-673 

13-63 

4290.542 

0.152 

•915 

2.056 

14.60 

0.143 

1-795 

1-935 

14.18 

0.123 

•  546 

1.676 

13.66 

4291.630 

0.151 

.897 

2.038 

14-47 

0.142 

1.778 

1.918 

14.06 

0.123 

•548 

1.678 

13.67 

4294.936 

0.152 

.901 

2.O42 

14.50 

0.142 

1.780 

1.920 

14.07 

0.122 

•534 

1.664 

13-56 

<t>  =  44?  2 

<t>  =  S9t2 

<t>  =  74!° 

4196.699 

0.090 

1.174 

.285 

12.72 

0.062 

0.806 

0.891 

12-35 

0.030 

0.404 

0-457 

11.77 

4I97-257 

0.089 

1.166 

.277 

12.65 

0.06  1 

0.796 

0.88  1 

12.21 

0.030 

0-393 

0.446 

11.49 

4203.730 

0.089 

1.166 

•277 

12.65 

0.062 

0.814 

0.899 

12.46 

0.031 

0.411 

0.464 

"•95 

4209.144 

0.091 

1.179 

.290 

12.77 

0.062 

0.803 

0.888 

12.31 

0.032 

0.426 

0.479 

12.34 

4216.136 

0.090 

1.171 

.282 

12.70 

0.061 

0.793 

0.878 

I2.I? 

0.031 

0.414 

0.467 

12.03 

4220.509 

0.091 

1.174 

.285 

12.73 

0.062 

0.804 

0.889 

12.32 

0.030 

0-395 

0.448 

"•54 

4232.887 

0.092 

1.190 

.301 

12.89 

0.062 

0.806 

0.891 

12-35 

0.032 

0.420 

0-473 

12.18 

4257-8I5 

0.092 

1.169 

.280 

12.68 

0.063 

0.805 

0.890 

12-34 

O.O32 

0.421 

0.474 

12.21 

4258-477 

0.088 

1.126 

•237 

12.25 

0.064 

0.822 

0-907 

12.57 

0.032 

0.415 

0.468 

12.05 

4265.418 

0.091 

1.158 

.269 

12.57 

0.062 

0-795 

0.880 

12.  2O 

0.033 

0.422 

0-475 

12.23 

4266.081 

0.090 

1.148 

-259 

12.47 

0.061 

0.775 

0.860 

11.92 

O.O3  I 

0.404 

0-457 

11.77 

4268.915 

0.091 

I-I57 

.268 

12.56 

0.06  1 

0.776 

0.86  1 

"•93 

0.032 

0.409 

0.462 

11.90 

4276.836 

0.090 

I-I33 

•244 

12.32 

0.062 

0.781 

0.866 

12.  OO 

0.030 

o-39i 

0-444 

11.44 

4284.838 

0.093 

1.174 

-285 

12.72 

0.062 

0.779 

0.864 

11.97 

0.032 

0.406 

0.459 

11.82 

4287.566 

0.090 

1.128 

-239 

12.27 

0.062 

0.786 

0.871 

I2.O7 

0.032 

0-415 

0.468 

12.05 

4288.310 

0.090 

1.138 

•249 

12.37 

0.062 

0.786 

0.871 

I2.O7 

0.031 

0-394 

0.447 

11.51 

'     4290-377 

0.089 

1.117 

.228 

12.  l6 

0.062 

0.777 

0.862 

"•PS 

0.032 

0.405 

0.458 

II.80 

4290.542 

0.090 

I-I37 

.248 

12.36 

0.063 

0.789 

0.874 

12.  II 

0.031 

0.400 

0-453 

11.67 

4291.630 

0.091 

1.149 

.260 

12.48 

0.062 

0.782 

0.867 

I  2.  02 

0.032 

0.405 

0.458 

11.80 

4294.936 

0.091 

1.144 

-255 

12.43 

0.062 

0.780        0.865 

11.99 

0.032 

0.411 

0.464 

"•95 

32     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD    OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4. —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  38.     1906,  Nov.  n,  nh  om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.2  ram.     Quality,  good. 


P-P 


O       228.6 

G-n    154.2 

P       -22.6 

D          3-1 

Diameter  171.6  mm 

Factor        1.027 


15-7 

16.0 

74.0 

ii-S 

i.  02  1 

30.7 

30.8 

59-  2 

6.2 

i.  006 

45.7 

45-8 

44.2 

4-4 

1.003 

60.7 

60.7 

29-3 

3-6 

i.  002 

75.7 

7S-7 

14-3 

3-2 

i.  002 

90.7 

90.7 

-0.7 

3-i 

i.  002 

*- 

-«* 

,- 

.4t3 

0  = 

29.3 

A 

t) 

.  +  ,, 

1 

A 

V 

,  +  ,, 

• 

A 

V 

V  ~\~  V. 

* 

4196.699 

0.148 

km 
1.926 

km 
2.067 

14.68 

0.138 

km 
.798 

km 
1.938 

14.20 

0.116 

km 
1.511 

km 
1.641 

13-36 

4197-257 

0.148 

.926 

2.067 

14.68 

0.142 

.848 

1.988 

14.56 

0.118 

1.536 

1.666 

13-56 

4203.730 

0.152 

•974 

2.II5 

I5.O2 

0-145 

.883 

2.023 

14.82 

O.I  22 

1.586 

1.716 

13-97 

4209.144 

0.151 

•957 

2.098 

14.90 

0.142 

.840 

.980 

14-50 

O.I24 

1.558 

1.688 

13-74 

4216.136 

0.148 

.914 

2.055 

14.59 

0.137 

.771 

.911 

14.00 

0.118 

1.526 

1.656 

13.48 

4220.509 

0.153 

•974 

2.II5 

I5.O2 

0.145 

.868 

.008 

14.71 

O.I24 

1.601 

I-73I 

14.09 

4232.887 

0.150 

.928 

2.069 

14.69 

0.140 

.801 

.941 

14.22 

O.I  2O 

1-542 

1.672 

13.61 

4257.815 

0.156 

.986 

2.127 

15.10 

0.146 

.822 

.962 

14-37 

0.126 

i.  608 

1.738 

14-15 

4258.477 

0.148 

.884 

2.025 

I4.38 

0.142 

.804 

•944 

14.24 

O.I2I 

i.54o 

1.670 

13.60 

4265.418 

0.152 

.928 

2.069 

14.69 

0.144 

.826 

.966 

14.40 

O.I22 

1.548 

1.678 

13.66 

4266.081 

0.156 

.978 

2.II9 

15.04 

0.148 

.874 

.014 

14.76 

O.I24 

1.568 

1.698 

13-82 

4268.915 

0.150 

.901 

2.042 

14.50 

0.142 

•797 

•937 

14.19 

O.II9 

1.508 

1.638 

13-33 

4276.836 

0.156 

.970 

2.  Ill 

14.99 

0.143 

.807 

•947 

14.26 

O.I2I 

1-529 

1.659 

i3-5i 

4284-838 

0.153 

•930 

2.071 

14.70 

0.142 

.790 

•930 

14.40 

O.I  2O 

1-513 

1-643 

13-38 

4287.566 

0.155 

•950 

2.091 

14.85 

0.145 

.828 

.968 

14.42 

0.122 

1-537 

1.667 

13-57 

4288.310 

0.154 

.940 

2.081 

14.78 

0.147 

.848 

.988 

14-56 

0.124 

1.561 

1.691 

13-77 

4290-377 

0.156 

•963 

2.IO4 

14.94 

0.140 

.762 

.902 

13-94 

0.123 

1-547 

1.677 

13-65 

4290.542 

0.151 

.899 

2.040 

14.48 

0.144 

.812 

•952 

14.3° 

O.I  2O 

1.511 

1.641 

13-36 

4291.630 

0.154 

•935 

2.076 

14-74 

0.140 

1.762 

.902 

13-94 

0.124 

1-559 

1.689 

13-75 

4294-936 

0.155 

•947 

2.088 

14.82 

0.146 

1.832 

.972 

14-45 

0.123 

1-544 

1.674 

13-63 

0  = 

44!  2 

0  = 

»* 

0  = 

74!o 

4196.699 

0.088 

1.149 

.260 

12.48 

0.059 

0.772 

0.857 

11.88 

O.O29 

0.382 

0-435 

11.20 

4197-257 

0.091 

1.185 

.296 

12.83 

0.060 

0.782 

0.867 

12.02 

0.030 

0-393 

0.446 

11.49 

4203.730 

0.092 

1.198 

•309 

12.96 

0.066 

0.855 

0.940 

I3.03 

0.036 

0.463 

0.516 

13.29 

4209.144 

0.094 

1.  221 

•332 

I3.I9 

0.062 

0.805 

0.890 

12.34 

0.034 

0-445 

0.498 

12.83 

4216.136 

0.088 

I.I4O 

•251 

12.39 

0.060 

0.780 

0.865 

11.99 

0.031 

0.403 

0.456 

"•75 

4220.509 

0.093 

1.192 

•303 

I2.9O 

0.062 

0.804 

0.889 

12.34 

0.036 

0.461 

0.5H 

13-24 

4232.887 

0.091 

1.164 

•275 

12.63 

0.064 

0.823 

0.908 

12.59 

0.035 

0-457 

0.510 

13.14 

4257-815 

0.093 

1.178 

.289 

12.77 

0.066 

0.844 

0.929 

12.88 

0.035 

0.454 

0.507 

13.06 

4258.477 

0.092 

I.I68 

•279 

12.67 

0.066 

0.839 

0.924 

12.81 

0.034 

0.438 

0.491 

12.65 

4265.418 

0.093 

1.176 

.287 

12.74 

0.063 

0.798 

0.883 

12.24 

0-033 

0.428 

0.481 

12.39 

4266.081 

0.092 

1.166 

•277 

12.65 

0.065 

0.827 

0.912 

12.64 

0.032 

0.413 

0.466 

12.00 

4268.915 

0.091 

I-I54 

.26S 

12-53 

0.062 

0.787 

0.872 

12.08 

0.036 

0.463 

0.516 

13.29 

4276.836 

0.093 

J-I73 

.284 

12.71 

0.063 

0.796 

0.881 

12.21 

0.032 

0.411 

0.464 

H-95 

4284.838 

0.092 

1.161 

.272 

I  2.60 

0.063 

0.794 

0.879 

12.  l8 

0.034 

0.436 

0.489 

12.60 

4287.566 

0.094 

1.181 

.292 

12.79 

0.065 

0.823 

0.908 

12-59 

0.032 

0.410 

0.463 

n-93 

4288.310 

0.094 

1.181 

.292 

12.79 

0.065 

0.819 

0.904 

12-53 

0.038 

0.483 

0.536 

13.82 

4290.377 

0.093 

1.170 

.281 

12.69 

0.064 

0.808 

0.893 

12.38 

0.034 

0.436 

0.489 

12.60 

4290.542 

0.093 

1.170 

I.28l 

12.69 

0.063 

0.794 

0.879 

12.18 

0.031 

0-395 

0.448 

11-54 

4291.630 

0.092 

I.I59 

1.270 

12.58 

0.062 

0.783 

0.868 

12.03 

0-035 

0-443 

0.496 

12.78 

4294-936 

0.093 

1.168 

1.279 

12.67 

0.070 

0.880 

0.965 

13-38 

0.033 

0.420 

0-473 

12.18 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


33 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  39.     1906,  Nov.  n,  nh  i$m  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  2.2  mm.    Quality,  good. 


Q       228.7 
0-n    154-3 

P         -22.6 

D          3.1 

Diameter  171.6  mm 

Factor        1.027 


p-p 

7T 

<t> 

•n 

secf 

o 

0 

o 

o 

15-7 

16.0 

74-o 

n.6 

I.O2I 

30.7 

30.8 

59-2 

6.1 

i.  006 

45-7 

45-8 

44-2 

4-4 

1.003 

60.7 

60.7 

29-3 

3-6 

i.  002 

75-7 

75-7 

14-3 

3-2 

1.002 

90.7 

90.7 

-0.7 

3-1 

1.002 

0  = 

-o!7 

0  = 

I4!3 

<#>  = 

2^3 

A 

» 

»  +  »! 

1 

A 

» 

r  +  Dj 

1 

A 

V 

H  +  Hj 

£ 

km 

km 

o 

km 

km 

0 

km 

km 

o 

4196.699 

0.150 

1.950 

2.091 

14.85 

0.135 

1-758 

1.898 

13-91 

0.118 

I-536 

1.666 

13-56 

4197.257 

0.150 

1.950 

2.091 

14.85 

0.137 

.782 

1.922 

14.08 

0.119 

I.548 

1.678 

13-66 

4203.730 

0.152 

-977 

2.118 

15-04 

0.141 

.828 

1.968 

14.42 

O.I  20 

1.560 

1.690 

13-76 

4209.144 

0.151 

•957 

2.098 

14.90 

0-143 

.847 

1.987 

14.56 

0.122 

1-584 

1.714 

13-95 

4216.136 

0.147 

•903 

2.044 

14-51 

0.142 

-837 

1-977 

14.48 

O.IlS 

1.526 

1.656 

13.48 

4220.509 

0-154 

.988 

2.129 

15.12 

0.144 

•853 

1-993 

14.60 

O.I25 

1.616 

1.746 

14.21 

4232.887 

0-153 

.964 

2.105 

14.94 

0.143 

-837 

1-977 

14.48 

0.122 

1-567 

1.697 

13.82 

4257-8I5 

0.151 

•924 

2.065 

14.66 

0.144 

•834 

1-974 

14.46 

0.126 

1.605 

1-735 

14.12 

4258.477 

0.153 

•947 

2.088 

14.82 

0.142 

.818 

1.958 

14-34 

O.I22 

1-554 

1.684 

13-71 

4265.418 

0.152 

•931 

2.072 

14.71 

0.146 

-844 

1.984 

14-35 

O.I2I 

1-537 

1.667 

13-57 

4266.081 

0.156 

.978 

2.119 

15-04 

0.144 

.819 

1-959 

14-35 

0.126 

1.598 

1.728 

14.07 

4268.915 

0.156 

•977 

2.118 

15-04 

0.144 

.820 

1.960 

14-36 

O.I22 

1.548 

1.678 

13.66 

4276.836 

0.152 

.919 

2.060 

14-63 

0-143 

•799 

1-939 

14.21 

0.123 

1-555 

1.685 

13.72 

4284.838 

0.153 

.926 

2.067 

14.68 

0.146 

-835 

1-975 

14-47 

0.124 

1-563 

1.693 

13-78 

4287.566 

0.156 

.964 

2.105 

14.94 

0.145 

.825 

1.965 

14.40 

0.123 

1-549 

1.679 

13.69 

4288.310 

0-154 

•937 

2.078 

14-75 

0.144 

.820 

1.960 

14-36 

O.I2I 

1.522 

1.652 

13-45 

4200.377 

0-153 

•923 

2.064 

14-65 

0.144 

.819 

1-959 

14-35 

O.I2I 

1.521 

1.651 

13-44 

4290.542 

0.152 

•913 

2.054 

14.58 

0.148 

-859 

1-999 

14-65 

O.I24 

1.561 

1.691 

13.77 

4291.630 

0.155 

•947 

2.088 

14.82 

0.144 

.818 

1.958 

14.35 

O.I2I 

1.521 

1.651 

13.44 

4294.936 

0-154 

•932 

2.073 

14.72 

0.145 

.819 

1-959 

14.35 

0.123 

1.546 

1.676 

13.64 

<t>  = 

44!* 

0  = 

59!* 

*  = 

74?° 

4196.699 

0.088 

.170 

.281 

12.68 

0.059 

0.772 

0.857 

11.88 

0.030 

0.398 

0-451 

11.52 

4197-257 

0.088 

.170 

.281 

12.68 

0.060 

0.792 

0.877 

12.  16 

0.029 

0.387 

0.440 

"•33 

4203.730 

0.092 

•195 

.306 

"•93 

0.063 

0.821 

0.906 

12.56 

0.034 

0.448 

0.501 

12.90 

4209.144 

0.095 

.231 

-342 

13-39 

0.064 

0.831 

0.916 

12.70 

0.034 

0.446 

0.499 

12.85 

4216.136 

0.089 

•153 

.264 

12.51 

0.061 

0.790 

0.875 

12.13 

0.030 

0.400 

0-453 

11.67 

4220.509 

0.093 

.196 

0.307 

12.94 

0.064 

0.829 

0.914 

12.67 

0.033 

0.436 

0.489 

12.60 

4232.887 

0.092 

.178 

.289 

12.76 

0.063 

0.812 

0.897 

12-43 

0.036 

0.470 

0.523 

13-47 

4257.815 

0.094 

.192 

•303 

12.90 

0.066 

0.839 

0.924 

12.81 

0.038 

0-453 

0.506 

13-03 

4258.477 

0.093 

.182 

•293 

12.80 

0.064 

0.8  1  8 

0.903 

12.52 

0.033 

0.427 

0.480 

12.36 

4265.418 

0.093 

.180 

.291 

12.78 

0.064 

0.817 

0.902 

12.50 

0.033 

0.427 

0.480 

12.36 

4266.081 

0.093 

.180 

.291 

12.78 

0.066 

0.838 

0.923 

12.80 

0-035 

0.452 

0.505 

13.01 

4268.915 

0.092 

.168 

•279 

12.67 

0.064 

0.812 

0.897 

12-43 

0-033 

0.426 

0.479 

12.34 

4276.836 

0.094 

.187 

.298 

12.85 

0.063 

0.798 

0.883 

12.24 

0.036 

0.461 

0.514 

13-24 

4284.838 

0.094 

.185 

.296 

12.83 

0.063 

0.796 

0.881 

12.21 

0.034 

0.436 

0.489 

12.60 

4287.566 

0.093 

•174 

.285 

12.72 

0.065 

0.820 

0.905 

12.54 

0.036 

0.460 

0.513 

13.21 

4288.310 

0.092 

.160 

.271 

12.58 

0.064 

0.809 

0.894 

12.39 

0.036 

0.460 

0-513 

13.21 

4290.377 

0.091 

•  144 

•255 

12.43 

0.064 

0.809 

0.894 

12.39 

0.032 

0.410 

0.463 

"•93 

4290.542 

0.093 

.170 

.281 

12.69 

0.063 

0-795 

0.880 

12.20 

0.032 

0.410 

0.463 

"•93 

4291.630 

0.094 

•  183 

•294 

12.81 

0.066 

0.829 

0.914 

12.67 

0.035 

0.446 

0.499 

12.85 

4294.936 

0.097 

.218 

•329 

13.16 

0.064 

0.804 

0.889 

12.32 

0.035 

0.446 

0.499 

12.85 

34     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 

TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  35.     1906,  Nov.  n,  ioh  om  G.  M.  T.    Measured  by  L.  onT\     Distance  from  Limb  2.2  mm.    Quality,  good. 


O       228.6 

9-n    154-2 

P        -22.6 


p-p 

15.5 
90-5 


7T  0 

15.8         74.2 
90.5        -0.5 


12.6 

3-' 


sec  i) 


I.02I 

i. 002 


D    3.1 

Diameter  171.6  mm 
Factor       1.027 


x 

<t>  = 

-o's 

<t>  — 

74!* 

A 

V 

«>  +  »! 

s 

A 

V 

i  +  t, 

I 

km 

km 

o 

km 

km 

. 

4196.699 

0.148 

•925 

2.066 

14.67 

0.029 

0.386 

0-439 

11-45 

4197-257 

0.150 

•950 

2.091 

14.85 

0.030 

0.397 

0.450 

n-73 

4203.730 

O.IS3 

.987 

2.128 

15.11 

0-033 

0.436 

0.489 

12.75 

4209.144 

0.154 

•995 

2.136 

15.16 

0.035 

0.462 

0-515 

13-43 

4216.136 

0.149 

.876 

2.017 

14-32 

0.030 

0-395 

0.448 

11.68 

4220.509 

0.153 

•974 

2.II5 

15.02 

0.032 

0.420 

0-473 

12.33 

4232-887 

0.153 

.967 

2.108 

14.97 

0-033 

0.430 

0.483 

12.60 

4257.815 

0-155 

•973 

2.114 

15.01 

0.034 

0-437 

0.490 

12.78 

4258.477 

0.151 

•923 

2.064 

14.65 

0.035 

0.452 

0-505 

13-17 

4265.418 

0.152 

1.927 

2.068 

14.68 

0.034 

0.436 

0.489 

12.75 

4266.081 

0.153 

1.940 

2.081 

14-78 

0-034 

0.436 

0.489 

12.75 

4268.915 

0.152 

1-925 

2.066 

14.67 

0.034 

0.436 

0.489 

12.75 

4276.836 

0.152 

.922 

2.063 

14.65 

0.034 

0.436 

0.489 

12.75 

4284.838 

0.154 

•943 

2.084 

14-79 

0.033 

0.425 

0.478 

12.46 

4287.566 

0.153 

•925 

2.066 

14.67 

0.034 

0-435 

0.488 

12-73 

4288.310 

0.154 

•938 

2.079 

14.76 

0.034 

0-435 

0.488 

12.73 

4290.377 

0.150 

.888 

2.029 

14.41 

0.034 

0-435 

0.488 

12.73 

4290.542 

0-153 

•923 

2.064 

14.65 

0.035 

0-445 

0.498 

12.99 

4291.630 

0-153 

.922 

2.063 

14.65 

0.033 

0.421 

0.474 

12.36 

4294.936 

0-154 

•931 

2.072 

14.71 

0.033 

0.420 

0-473 

12-33 

Plate  u  39J.     1906,  Dec.  18,  5h  50™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  4.  i  mm.     Quality,  good. 


O       265.9 

G-n    191.5 

P       -8.8 


P-P 

59-9 
74-9 
89.9 


59-9 
74-9 
89.9 


30.1 


1.4 


secv 

i.ooo 
i.ooo 
i.ooo 


D     -1.5 

Diameter  175.2  mm 
Factor        1.049 


X 

0  = 

o!i 

<t>  = 

IS?I 

<t>  = 

30?i 

A 

V 

»+»! 

{ 

A 

V 

JI+Dj 

i 

A 

V 

»  +  », 

£ 

km 

km 

O 

km 

km 

. 

km 

km 

0 

4196.699 

0.148 

1.963 

2.104 

14.94 

0.138 

I.833 

1-973 

14-52 

0.119 

1-577 

1.707 

14.02 

4197-257 

0.148 

1.963 

2.104 

14.94 

0.138 

1.833 

1-973 

14-52 

0.120 

1.587 

1.717 

14.10 

4203.730 

0.150 

1.985 

2.126 

15-09 

0.141 

1.837 

1.977 

14.54 

O.II9 

1-575 

I.705 

14.00 

4209.144 

0-153 

2.021 

2.162 

15-35 

0.142 

1.871 

2.  Oil 

14.79 

O.I22 

1-594 

1.724 

14.16 

4216.136 

0.146 

1.926 

2.067 

14.67 

0.139 

1.836 

1.976 

14.54 

0.118 

I.5S6 

1.686 

13.85 

4220.509 

0.151 

1.974 

2.115 

15.02 

0.141 

1-855 

1-995 

14.68 

0.122 

1.586 

1.716 

14.09 

4232.887 

0.150 

1.958 

2.099 

14.90 

0.142 

1.846 

1.986 

14.61 

O.I22 

1.582 

1.712 

14.06 

4257.815 

0.150 

1-947 

2.088 

14.82 

0.144 

1.868 

2.008 

14-77 

O.I24 

1-597 

1.727 

14.19 

4258.477 

0.150 

1.946 

2.087 

14.82 

0.141 

1.823 

1.963 

14.44 

0.120 

I-5S2 

.682 

13.82 

4265.418 

0.152 

1.965 

2.106 

14-95 

0.142 

1.831 

1.971 

14-50 

0.123 

1-584 

•714 

14.08 

4266.081 

0.156 

2.016 

2-157 

15.31 

0.143 

1.850 

1.990 

14.64 

O.I2I 

1-563 

•693 

13.91 

4268.915 

0.149 

1.924 

2.065 

14.66 

0.140 

1.805 

1-945 

14-31 

0.122 

1-566 

.696 

13.93 

4276.836 

0.152 

1.956 

2.097 

14.89 

0.142 

1-823 

1.963 

14.44 

0.123 

1.580 

.710 

14.05 

4284.838 

0.153 

1.963 

2.104 

14.94 

0.145 

i.  860 

2.000 

14.71 

O.I2I 

I-556 

.686 

13-85 

4287.566 

0-153 

1.967 

2.108 

14.97 

0.144 

1.848 

1.988 

14.63 

O.I22 

1.562 

.692 

13.90 

4288.310 

0-154 

1.972 

2.113 

15.00 

0.141 

i.  808 

1.948 

14-33 

O.I24 

1-587 

.717 

14.10 

4290.377 

0.151 

1-933 

2.074 

14.72 

0.141 

1.810 

1.950 

14.35 

O.I  2O 

1-537 

.667 

13.69 

4290.542 

0.150 

1.922 

2.063 

14.65 

0-145 

1.858 

1.998 

14.70 

0.125 

1-599 

.729 

14.20 

4291.630 

0.152 

1-949 

2.090 

14.84 

0.140 

1.796 

1.936 

14.24 

0.123 

1-575 

1-705 

14.00 

4294.936 

0.153 

1-959 

2.IOO 

14.91 

0.142 

1.815 

1-955 

14-38 

0.122 

1.560 

1.690 

13.88 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


35 


Plate 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
40.    1906,  Dec.  18,  6b  40™  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  4.1  mm.    Quality,  good. 


O       265.9 

o-n   191.5 

P       -8.8 

D       -i.S 

Diameter  175.6  mm 

Factor        1.049 


P-P 

59-9 
74-9 
89.9 


59-9 
74-9 
89.9 


30.1 

O.I 


i-S 
1.4 


sec>; 

1. 000 
I.OOO 
1. 000 


<t>  = 

o!i 

0  = 

°!i 

<#>  = 

is!i 

A 

V 

f  +  tlj 

£ 

A 

fl 

T  +  fl! 

1 

A 

V 

!  +  «, 

1 

km 

km 

o 

km 

km 

0 

km 

km 

« 

4196.699 

0.148 

1.964 

2.105 

14.94 

0.150 

1.990 

2.131 

I5-I3 

0.138 

1-833 

1-973 

14-50 

4197.257 

0.148 

1.964 

2.105 

14.94 

0.150 

1.990 

2.131 

IS-I3 

0-139 

1.843 

1.983 

14-58 

4203.730 

0.152 

2.013 

2-154 

15-29 

0.149 

1-975 

2.116 

15.02 

0.141 

1.863 

2.003 

14.72 

4209.144 

0.149 

1.966 

2.107 

14.96 

0.150 

1.984 

2.125 

15.09 

0.141 

1.805 

1-945 

14-30 

4216.136 

0.151 

1.986 

2.127 

15.10 

0.148 

I-95I 

2.092 

14-85 

0.141 

1.858 

1.998 

14.68 

4220.509 

0.150 

1-975 

2.116 

15.02 

0.152 

2.OOI 

2.142 

15.21 

0.140 

1.841 

1.981 

14-56 

4232.887 

0.149 

1-954 

2.095 

14.87 

0.150 

1.966 

2.IO7 

14.96 

0.141 

0.846 

1.986 

14.60 

4257.815 

0.152 

1.969 

2.  IIO 

14.98 

o.iSS 

2.013 

2.154 

I5.29 

0.142 

1.843 

1.983 

14.58 

4258.477 

0.152 

1.968 

2.IO9 

14-97 

0.149 

•936 

2.077 

14-74 

0.139 

1.802 

1.942 

14.27 

4265.418 

0.150 

1.940 

2.081 

14-77 

0.151 

•954 

2.095 

14.87 

0.143 

1.851 

1.991 

14-63 

4266.081 

0-153 

1.976 

2.II7 

15-03 

0.152 

.960 

2.IOI 

14.92 

0.143 

1.850 

1.990 

14.63 

4268.915 

0.152 

1-959 

2.  TOO 

14.91 

0.150 

.938 

2.079 

14.76 

0.143 

1.849 

1.989 

14.62 

4276.836 

0-153 

1.971 

2.  112 

14.99 

0.151 

•945 

2.086 

14.81 

0.144 

1.853 

1-993 

14.65 

4284.838 

0.152 

1-953 

2.094 

14.87 

0.152 

J-953 

2.094 

14.87 

0.142 

1.824 

1.964 

14.44 

4287.566 

0.148 

1.900 

2.O4I 

14.49 

0.152 

I-95I 

2.092 

14.85 

0.140 

1-797 

1-937 

14.24 

4288.310 

0.151 

1-937 

2.078 

14-75 

0.156 

1.998 

2.139 

15-18 

0.143 

1.848 

1.988 

14.61 

4290.377 

0.152 

1.947 

2.088 

14.82 

0.151 

1.936 

2.077 

14-74 

0.140 

1.796 

1.936 

14-23 

4290.542 

0.150 

1.921 

2.o62 

14.64 

0.151 

1.936 

2.077 

14.74 

0.144 

1.844 

1.984 

14-58 

4291.630 

0.150 

1.921 

2.062 

14.64 

0.152 

1.946 

2.087 

14.81 

0.141 

i.  806 

1.946 

14.30 

4294.936 

0.152 

1-945 

2.086 

14.81 

0.150 

1.919 

2.O6O 

14.62 

0.143 

1.831 

1.971 

14.49 

0  = 

isli 

0  = 

3o!i 

<f>  = 

so!i 

4196.699 

0-139 

1.843 

1.983 

14.58 

O.I  20 

•592 

1.722 

I4-I3 

0.119 

1.581 

1.711 

14.04 

4197.257 

0.140 

1.859 

1.999 

14.69 

O.II9 

.578 

1.708 

14.02 

0.123 

1-633 

1-763 

14-47 

4203.730 

0.141 

1.867 

2.007 

14-75 

0.123 

.631 

1.761 

14-45 

O.I22 

1.616 

1.746 

14-33 

4209.144 

0-143 

1.887 

2.027 

14.90 

0.122 

.610 

1.740 

14.28 

0.120 

1-584 

1.714 

14.06 

4216.136 

0.140 

1.843 

1.983 

14.58 

O.II7 

•541 

1.671 

I3-7I 

O.IlS 

I-556 

1.686 

13-84 

4220.509 

0.140 

1.841 

1.981 

14.56 

O.I  21 

•591 

1.721 

14.12 

O.I  2O 

1.580 

1.710 

14-03 

4232.887 

0.143 

1.872 

2.012 

14.79 

O.I  2O 

-561 

1.691 

13-88 

0.122 

1-597 

1.727 

14.17 

4257.815 

0.141 

1.828 

1.968 

14.46 

O.I2I 

•559 

1.689 

13.86 

O.I22 

1-585 

1.715 

14.07 

4258.477 

0.140 

1.813 

1-953 

14-35 

O.I24 

.607 

1-737 

14.25 

O.I22 

1.581 

1.711 

14.04 

4265.418 

0.141 

1.825 

1.965 

14.44 

O.I2I 

.560 

1.690 

13-87 

0.124 

1.604 

1-734 

14-23 

4266.081 

0.140 

1.810 

1-950 

14-33 

0.124 

.604 

1-734 

I4-23 

0.123 

1.589 

1.719 

14.11 

4268.915 

0.142 

1-834 

1-974 

14-51 

O.I  2O 

•547 

1.677 

I3-76 

0.123 

1.588 

1.718 

14.10 

4276.836 

0.145 

1.871 

2.  on 

14.78 

O.I  22 

-570 

1.700 

13-95 

O.I22 

1.566 

1.696 

13.92 

4284.838 

0.140 

1.799 

1-939 

14-25 

O.I  21 

•552 

1.682 

13.80 

O.I2I 

1-552 

1.682 

13.80 

4287.566 

0.144 

1.848 

1.988 

14.61 

O.I2I 

•551 

1.681 

13-79 

O.I22 

1-563 

1.693 

13.89 

4288.310 

0.141 

1.808 

1.948 

14-32 

O.I  20 

•540 

1.670 

13.70 

O.I22 

1.562 

1.692 

13-88 

4290.377 

0.140 

1.796 

1.936 

14-23 

O.II9 

•525 

I-6S5 

I3-58 

O.I  2O 

1.540 

1.670 

13.70 

4290.542 

0.140 

1.796 

1.936 

14-23 

O.I  21 

•550 

i.  680 

13-79 

O.II7 

1.499 

1.629 

13-37 

4291.630 

0.147 

1.884 

2.024 

14.88 

O.I  21 

•550 

i.  680 

13-79 

O.I2I 

i-SSo 

i.  680 

13-79 

4294.936 

0.142 

1.815 

1-955 

14-37 

O.I22 

-560 

1.690 

13.87 

O.I22 

1-560 

1.690 

13-87 

36    AN   INVESTIGATION   OF   THE   ROTATION   PERIOD    OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4. —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  41.     1906,  Dec.  18,  6h  so""  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  4.1  mm.     Quality,  good. 


O       265.9 

O-S2     191.5 

P       -8.8 

D       -1.5 

Diameter  175.6  mm 

Factor        1.049 


P-P 

59-9 
74-9 
89.9 


59-9 
74-9 
89.9 


t> 

30.1 
15.1 

O.I 


1.4 


secy 

I.OOO 
I.OOO 
I.OOO 


*- 

0*1 

*- 

«* 

»- 

X* 

A 

» 

.  +  „ 

1 

A 

V 

,-M, 

£ 

A 

t) 

.  +  ., 

• 

4196.699 

0.145 

km 
1.927 

km 
2.068 

14.68 

0.145 

km 
1.927 

km 
2.068 

14.68 

0.136 

km 
1.  806 

km 
1.946 

14.30 

4197-257 

0.146 

1.938 

2.079 

14.76 

0.144 

I.9I3 

2.054 

14.58 

0.138 

1.832 

1.972 

14.49 

4203.730 

0.147 

1.946 

2.087 

14.82 

0.147 

1.946 

2.087 

14.82 

0.141 

I.86I 

2.OOI 

14.71 

4209.144 

0.148 

1.958 

2.099 

14.90 

0.148 

1-954 

2.095 

14.87 

0.140 

1-794 

•934 

14.21 

4216.136 

0.146 

1.926 

2.067 

14.67 

0.145 

1.912 

2.053 

14.58 

0.138 

1.820 

.960 

14.41 

4220.509 

0.148 

1.949 

2.090 

14.84 

0.148 

1-945 

2.086 

14.81 

0.141 

1.856 

.990 

14-63 

4232.887 

0.150 

1.965 

2.106 

14-95 

0.150 

1.965 

2.106 

14-95 

0-139 

1.818 

•958 

14-39 

4257-815 

0-153 

1.985 

2.126 

15.09 

0.150 

1.946 

2.087 

14.82 

0.141 

1.828 

.968 

14.46 

4258.477 

0.148 

1.922 

2.063 

14-65 

0.150 

1.946 

2.087 

14.82 

0.140 

1.813 

•953 

14-35 

4265.418 

0.152 

1.969 

2.  no 

14.98 

0.152 

1.968 

2.109 

14.97 

0.142 

1.836 

•976 

14.52 

4266.081 

0.151 

1-954 

2.095 

14.87 

0.148 

1.919 

2.060 

14-63 

0.142 

1.836 

1.976 

14-52 

4268.915 

0.151 

1-952 

2.093 

14.86 

0.149 

1.928 

2.069 

14.69 

0.142 

1-835 

1-975 

14.52 

4276.836 

0.152 

1.960 

2.IOI 

14.92 

0.152 

J-959 

2.IOO 

14.91 

0.141 

1.817 

1-957 

14-38 

4284.838 

0.150 

1.928 

2.069 

14.69 

0.150 

1.928 

2.069 

14.69 

0.142 

1.807 

1-947 

14-31 

4287.566 

0.151 

1-937 

2.078 

14-75 

0.150 

1.923 

2.064 

14-65 

0.141 

1.809 

1.949 

14-32 

4288.310 

0.152 

2.092 

14.85 

0.151 

1-933 

2.074 

14.72 

0.140 

1-794 

1-934 

14.21 

4290.377 

0.151 

I-936 

2.077 

14-75 

0.149 

1.912 

2-053 

14.58 

0.142 

1.803 

1-943 

14.28 

4290.542 

0.151 

1.936 

2.077 

14-75 

0.150 

1.922 

2.063 

14-65 

0.140 

1.792 

1.932 

14.20 

4291.630 

0.151 

1.936 

2.077 

14-75 

0.150 

1.922 

2.063 

14.65 

0.141 

1.807 

1.947 

I4-3I 

4294-936 

0.151 

1-934 

2.075 

14-74 

0.152 

1-945 

2.086 

14.81 

0.140 

1.791 

I-93I 

14.19 

*- 

.,:, 

*- 

* 

*- 

30!  i 

4196.699 

0.136 

1.806 

1.946 

14-30 

O.I2I 

1.607 

1-737 

14.25 

0.115 

•525 

1-655 

I3-S8 

4197-257 

0.136 

i.  806 

1.946 

14-30 

O.I2I 

1.607 

1-737 

14-25 

0.117 

•551 

.681 

13-79 

4203.730 

0-139 

1.840 

1.980 

14-55 

O.I  2O 

1-590 

1.720 

14.11 

0.119 

•574 

.704 

13.98 

4209.144 

0.140 

1.848 

1.988 

14.61 

O.II8 

-558 

1.688 

13-85 

0.119 

•572 

.702 

13-97 

4216.136 

0-137 

1.805 

1-945 

14-30 

O.IlS 

-556 

1.686 

13-84 

0.116 

•529 

•659 

13.61 

4220.509 

0.138 

1.814 

1-954 

14.36 

O.IlS 

•554 

1.684 

13.82 

0.120 

-578 

.708 

14.02 

4232.887 

0.141 

1-794 

1-934 

14.21 

O.I  2O 

-571 

1.701 

13.96 

0.119 

1-561 

.691 

13.88 

4257-815 

0.142 

1.843 

1.983 

14-58 

0.122 

.585 

I-7I5 

14.07 

O.I  2O 

1-554 

.684 

13.82 

4258.477 

0.140 

1.812 

1-952 

14-34 

0.123 

-591 

1.721 

14.12 

O.I2I 

1-565 

-695 

I3-9I 

4265.418 

0.140 

1.809 

1-949 

14-32 

O.I2I 

-567 

1.697 

13-93 

0.120 

1-552 

.682 

13.80 

4266.081 

0.141 

1.826 

1.966 

14-45 

O.I2I 

•567 

1.697 

13-93 

O.I22 

1-576 

.706 

14.00 

4268.915 

0.141 

1.824 

1.964 

14.44 

0.123 

.588 

1.718 

14.10 

O.I  2O 

.681 

13-79 

4276.836 

0.142 

1.832 

1.972 

14.49 

O.I22 

•574 

1.704 

13.98 

0.123 

1-583 

•713 

14.06 

4284.838 

0.143 

1.839 

1.979 

14-55 

O.I22 

.567 

1.697 

13-93 

O.II9 

1-530 

.660 

13.62 

4287.566 

0.141 

1.807 

1.947 

14-31 

O.I22 

-566 

1.696 

13.92 

O.I22 

I-57I 

.701 

13.96 

4288.310 

0.141 

1.807 

1.947 

14-31 

O.I24 

•591 

1.721 

14.12 

O.I2I 

1.562 

.692 

13.88 

4290.377 

0.142 

1.819 

1-959 

14.40 

0.123 

-577 

1.707 

14.01 

O.I2I 

1.562 

.692 

13-88 

4290.542 

0.142 

1.819 

1-959 

14.40 

0.122 

-566 

1.696 

13.92 

0.123 

I-S7S 

•705 

13-99 

4291.630 

0.142 

1.817 

1-957 

14.38 

O.II8 

1.514 

1.644 

13-49 

O.I22 

1-565 

1.695 

13-91 

4294.936 

0-143 

1.831 

1.971 

14.49 

O.I22 

1.560 

1.690 

13-87 

O.I22 

1-564 

1.694 

13.90 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


37 


TABLE  4. —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1906-1907  —  Continued. 
Plate  1046.     1906,  Dec.  18,  ioh  30™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  4.1  mm.    Quality,  good. 


O       266.1 

O-O    191.7 

P       -8.8 

D       -1.5 

Diameter  175.0  mm 

Factor       1.047 


P-P 

30.6 
45-6 


30.6 
45-6 


59-4 
44.4 


2.9 

2.1 


seen 


I.OOI 
I.OOI 


0  = 

44?4 

0  = 

44?4 

0  = 

44?4 

X 

A 

» 

f  +  «l 

e 

A 

V 

H  +  Uj 

{ 

A 

V 

f  +  Pj 

E 

km 

km 

. 

km 

km 

o 

km 

km 

o 

4196.699 

0.088 

I.I68 

.281 

12.73 

0.086 

1.138 

•251 

12.43 

0.088 

.164 

1.277 

12.69 

4197.257 

0.088 

1.168 

.281 

12.73 

0.088 

1.163 

.276 

12.68 

0.089 

.178 

1.291 

12.83 

4203.730 

0.090 

1.187 

.300 

12.92 

0.090 

.187 

.300 

12.92 

0.092 

.216 

•329 

13.21 

4209.144 

0.090 

1.186 

•299 

12.91 

0.090 

.186 

.299 

12.91 

0.092 

.211 

-324 

13.16 

4216.136 

0.089 

1.170 

-283 

12.75 

0.091 

.198 

•3" 

13-03 

0.088 

•159 

.272 

12.64 

4220.509 

0.091 

1-193 

-306 

12.98 

0.091 

.197 

.310 

13.02 

0.092 

.208 

.321 

13-13 

4232-887 

0.092 

I.2OI 

.314 

13.06 

0.093 

•215 

.328 

13.20 

0.090 

.176 

.289 

12.81 

4257.815 

0.093 

1.205 

-318 

13.10 

0.093 

.204 

•317 

13.09 

0.092 

.189 

.302 

12.94 

4258.477 

0.092 

1.187 

.300 

12.92 

0.093 

.204 

I-3I7 

13.09 

0.090 

-I6S 

.278 

12.70 

4265.418 

0.095 

1.226 

•339 

13-31 

0.094 

1.209 

1.322 

13-14 

0.093 

.199 

.312 

13-04 

4266.081 

0.092 

1.185 

.298 

12.90 

0.092 

1-185 

1.298 

12.90 

0-092 

1.188 

.301 

12-93 

4268.915 

0.092 

1.182 

•295 

12.87 

0.092 

1.184 

1.297 

12.89 

0.093 

1.198 

•3" 

13.02 

4276.836 

0.091 

1.171 

.284 

12.76 

0.093 

1.196 

1.309 

13.01 

0.092 

1.185 

.298 

12.90 

4284.838 

0.092 

1.180 

•293 

12.84 

0.092 

1.180 

1.293 

12.85 

0.090 

I-I59 

.272 

12.64 

4287.566 

0.096 

1.231 

•344 

13-35 

0.092 

1.179 

1.292 

12.84 

0.092 

1.179 

.292 

12.84 

4288.310 

0.090 

I-I54 

.267 

12.59 

0.092 

1.179 

1.292 

12.84 

0.091 

1.168 

.281 

12.73 

4290.377 

0.090 

1.149 

.262 

12.54 

0.093 

1.163 

1.276 

12.68 

0.090 

I-I54 

•277 

12.69 

4290.542 

0.089 

1.139 

.252 

12.44 

0.091 

1.149 

1.262 

12-54 

0.092 

1.178 

.291 

12.83 

4291.630 

0.091 

1.164 

.279 

12.71 

0.092 

1.178 

1.291 

12.83 

0.091 

1.167 

.280 

12.72 

4294.936 

0.092 

1.177 

.290 

12.82 

0.094 

1.198 

1.311 

13-03 

0.092 

1.177 

.290 

12.82 

0  = 

S9!4 

0  = 

S9°A 

0  = 

S9t4 

4196.699 

0.058 

0.766 

0.852 

11.88 

0.058 

0.768 

0-854 

11.91 

0.060 

0-793 

0.879 

12.26 

4197.257 

0.056 

0.736 

0.822 

11.46 

0.06  1 

0.804 

0.890 

12.41 

0.057 

0-757 

0.843 

11.76 

4203.730 

0.060 

0.792 

0.878 

12.25 

0.06  1 

0.803 

0.889 

12.40 

0.064 

0.844 

0-930 

12.97 

4209.144 

0.062 

0.8  1  6 

0.902 

12.58 

0.062 

0.816 

0.902 

12.58 

0.062 

0.816 

0.902 

12.58 

4216.136 

0.060 

0.790 

0.876 

12.22 

0.06  1 

0.801 

0.887 

12.37 

0.058 

0.764 

0.850 

11.85 

4220.509 

0.062 

0.814 

0.900 

12-55 

0.062 

0.814 

0.900 

12.55 

0.061 

0.803 

0.889 

12.40 

4232.887 

0.062 

0.812 

0.898 

12.52 

0.063 

0.822 

0.908 

12.66 

0.065 

0.848 

0-934 

13-03 

4257.815 

0.064 

0.828 

0.914 

12-74 

0.064 

0.825 

0.911 

12.71 

0.062 

0.802 

0.888 

12.38 

4258.477 

0.06  1 

0-793 

0.879 

12.26 

0.062 

0.800 

0.886 

12.36 

0.062 

0.839 

0.925 

12.90 

4265.418 

0.065 

0.847 

0-933 

13.01 

0.06  1 

0.788 

0.874 

12.19 

0.064 

0.829 

0.915 

12.76 

4266.081 

0.064 

0.827 

0.913 

12-73 

0.064 

0.824 

0.910 

12.69 

0.065 

0.839 

0.925 

12.90 

4268.915 

0.063 

0.812 

0.892 

12.44 

0.065 

0.838 

0.924 

12.89 

0.063 

0.809 

0.875 

12.  2O 

4276.836 

0.062 

0.802 

0.888 

12.38 

0.062 

0-797 

0.883 

12.32 

0.062 

0.797 

0.883 

12.32 

4284.838 

0.06  1 

0.788 

0.874 

12.19 

0.065 

0.831 

0.917 

12.79 

0.063 

0.806 

0.892 

12.44 

4287.566 

0.063 

0.809 

0.895 

12.48 

0.063 

0.805 

0.891 

12.43 

0.061 

0.781 

0.867 

I2.O9 

4288.310 

0.062 

0-795 

0.881 

12.29 

0.064 

0.820 

0.906 

12.64 

0.062 

Q-795 

0.881 

12.29 

4290.377 

0.060 

0.770 

0.856 

11.94 

0.062 

0.794 

0.880 

12.27 

0.063 

0.805 

0.891 

12.43 

4290.542 

0.061 

0.784 

0.870 

12.13 

0.062 

0-794 

0.880 

12.27 

0.063 

0.805 

0.891 

12.43 

4291.630 

0.062 

0-794 

0.880 

12.27 

0.063 

0.804 

0.890 

12.41 

0.062 

0-794 

0.880 

12.27 

4294.936 

0.062 

0.794 

0.880 

12.27 

0.06  1 

0.780 

0.866 

12.08 

0.063 

0.804 

0.890 

12.41 

38     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4. — RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  47.     1906,  Dec.  18,  lo11  50™  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  3.9  mm.    Quality,  good. 


O        266.1 

o-n  191.7 

P        -8.8 

D        -1.5 

Diameter  175.0  mm 

Factor        1.047 


p— P           TT  <t>  ij  seci? 

30.6  30.6  59.4  2.9  i.ooi 

38.1  38.1  51.9  2.4  i.ooi 

45.6  45.6  44.4  2.1  I.OOI 

54.6  54.6  35.4  1.8  i.ooo 


0  = 

35t4 

0  = 

35!4 

0  = 

44t4 

A 

D 

H-* 

' 

A 

V 

.  +  ., 

• 

A 

V 

,  +  „ 

« 

4196.699 

o.i  06 

km 
1.410 

km 

1-535 

13-37 

O.IOI 

km 

1.386 

km 
1.511 

13.16 

0.086 

km 
.169 

km 
.282 

12.74 

4197-257 

0.107 

1.417 

1-542 

13-43 

0.103 

1.366 

1.491 

12.99 

0.088 

.169 

.282 

12.74 

4203.730 

0.105 

1.386 

1.511 

13.16 

0.108 

1.427 

1-552 

I3-52 

0.092 

.20? 

.320 

13.12 

4209.144 

0.108 

1.426 

1.551 

13-51 

0.106 

1.398 

I-523 

13.26 

0.091 

.197 

.310 

13.02 

4216.136 

0.109 

1-434 

1-559 

13.58 

0.102 

1.392 

I-5I7 

13.21 

0.090 

.185 

.298 

12.90 

4220.509 

0.108 

1.418 

1-543 

13-44 

o.i  06 

1-391 

1.516 

13.20 

0.092 

.209 

.322 

I3-I4 

4232.887 

0.108 

I-4IS 

1-540 

13-41 

0.104 

1.405 

1-530 

13-33 

0.091 

.187 

.300 

12.92 

4257.815 

0.108 

1.400 

I-S2S 

13.28 

0.108 

1-397 

1-522 

13.26 

0.092 

-205 

•315 

13-07 

4258.477 

0.109 

1.410 

1-535 

13-37 

0.107 

1.386 

1.511 

13.16 

0.092 

.202 

•315 

13-07 

4265.418 

0.109 

1.408 

J-533 

13-35 

0.108 

1-394 

I-5I9 

13-23 

0.095 

.224 

1-337 

13-29 

4266.081 

O.III 

1.432 

1-557 

13-56 

o.i  06 

1.369 

1-494 

13.01 

0.093 

.2OO 

I-3I3 

13-05 

4268.915 

O.II2 

1-445 

1-570 

13.67 

0.108 

1-393 

1.518 

13.22 

0.093 

.199 

1.312 

13.04 

4276.836 

O.II4 

1.464 

1.589 

13.84 

O.IIO 

i-4i5 

•540 

I3-4I 

0.094 

.207 

1.320 

13.12 

4284.838 

O.IIO 

1.410 

1-535 

13-37 

O.III 

1.426 

•551 

I3-5I 

0.094 

.204 

I-3I7 

13.09 

4287.566 

0.109 

1-395 

1.520 

13-24 

0.107 

1-370 

•495 

13.02 

0.092 

.l8o 

1.293 

12.85 

4288.310 

0.108 

1-385 

1.510 

13-15 

0.108 

1.384 

•509 

I3-I4 

0.096 

.229 

1-342 

13-34 

4290.377 

0.108 

1.384 

1.509 

13-14 

0.109 

1-395 

.520 

13-24 

0.092 

I.I79 

1.292 

12.84 

4290.542 

0.108 

1-384 

1.509 

13-14 

0.108 

1.384 

•509 

13-14 

0.092 

I.I79 

1.292 

12.84 

4291.630 

0.108 

1.384 

1.509 

13-14 

0.108 

1-379 

•504 

13.10 

0.093 

I.I89 

1.302 

12.94 

4294.936 

O.II2 

1-433 

I.5S8 

13-57 

0.106 

1-354 

•479 

12.88 

0.093 

1.189 

1.302 

12.94 

0  = 

*9 

0  = 

5:!9 

0  = 

S9?4 

4196.699 

O.072 

0-955 

1.056 

12.15 

0.073 

0.967 

i.  068 

12.28 

0.060 

0-793 

0.879 

12.26 

4197-257 

0.073 

0.966 

1.067 

12.27 

0.075 

0-995 

1.096 

12.65 

0.057 

0.757 

0.843 

11.76 

4203.730 

0.073 

0.964 

1.065 

12.25 

0.075 

0.994 

1.095 

12.64 

0.058 

0.766 

0.852 

11.88 

4209.144 

0.074 

0.977 

1.078 

12.40 

0.074 

0.978 

1.079 

12.41 

0.064 

0.849 

0-935 

13-04 

4216.136 

0.074 

0.976 

1.077 

12.39 

0.074 

0.977 

1.078 

12.40 

0.060 

0.790 

0.876 

12.22 

4220.509 

0.075 

0.985 

i.  086 

12.49 

0.075 

0.983 

1.084 

12.47 

0.06  1 

0.800 

0.886 

12.36 

4232.887 

0.078 

1.014 

1.115 

12.82 

0.073 

0-955 

1.056 

12.15 

0.062 

0.808 

0.894 

12.47 

4257-815 

0.076 

0.984 

1.085 

12.48 

0.076 

0.985 

i.  086 

12.49 

0.064 

0.828 

0.914 

12.75 

4258.477 

O.oSo 

1-035 

1.136 

13-07 

0.076 

0.985 

i.  086 

12.49 

0.065 

0.846 

0.932 

13.00 

4265.418 

0.076 

0.982 

1.083 

12.46 

0.074 

0-959 

i.  060 

12.19 

0.065 

0.845 

0.931 

12.98 

4266.081 

0.079 

i.  020 

1.  121 

12.89 

0.078 

1.009 

i.  no 

12.87 

0.067 

0.865 

I3-24 

4268.915 

0.074 

0-957 

1.058 

12.17 

0.075 

0.969 

1.070 

12.32 

0.062 

0.798 

0.884 

12.33 

4276.836 

0.079 

1.017 

1.118 

12.86 

0.074 

0-953 

1.054 

12.13 

0.062 

0.797 

0.883 

12.32 

4284.838 

0.077 

0.991 

1.092 

12.56 

0.076 

0.976 

1.077 

12.39 

0.06  1 

0.785 

0.871 

12.15 

4287.566 

0.078 

I.OOI 

I.IO2 

12.68 

0.079 

I.OIO 

i.  in 

12.88 

0.065 

0.833 

0.919 

12.82 

4288.310 

0.077 

0.986 

I.OS? 

12.50 

0.081 

1.034 

I-I35 

13-05 

0.064 

0.819 

0.905 

12.62 

4290.377 

0.078 

I.OOO 

I.IOI 

12.67 

0.080 

1.023 

1.124 

12.93 

0.064 

0.819 

0.905 

12.62 

4290.542 

O.O8O 

1.024 

1.125 

12.94 

0.077 

0.986 

1.087 

12.50 

0.064 

0.819 

0.905 

12.62 

4291.630 

0.079 

I.OIO 

I.  Ill 

12.87 

0.079 

1.009 

i.  no 

12.87 

0.063 

0.805 

0.891 

12.43 

4294.936 

0.075 

0-959 

1.  060 

12.19 

0.078 

0.998 

1.099 

12.65 

0.062 

0-794 

0.880 

12.27 

RESULTS   FOR   INDIVIDUAL  PLATES.      OBSERVATIONS   OF    1906-1907. 


39 


Plate 


TABLE  4.  —  RESULTS  FOB  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
50.     1907,  Feb.  3,  $h  40""  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  3.5  mm.    Quality,  good. 


O 

0-0 
P 
D 


313.8 

239-4 

13.0 

-6.3 


Diameter  174.1  mm 
Factor        1.042 


p-p 

7T 

4> 

1 

sec  17 

10.5 

12.2 

77°8 

3°-9 

1.166 

19.5 

20-S 

69-S 

18.1 

1.052 

35-5 

36.0 

54-0 

10.6 

1.017 

Si-5 

51.8 

38-2 

7-9 

1.009 

66.5 

66.7 

23-3 

6.8 

1.008 

82.3 

82.5 

7-5 

6-3 

1.006 

<t>  =  ?!s 

<t>  -  13°3 

<t>  =  38t2 

A 

» 

V  +  »! 

{ 

A 

V 

»  +  »! 

« 

A 

» 

»  +  », 

{ 

km 

km 

O 

km 

km 

. 

km 

km 

e 

4196.699 

0.141 

1.861 

2.OO2 

14-32 

0.128 

1.700 

1.834 

14.18 

0.104 

1.383 

.500 

13-55 

4197-257 

0.141 

1.861 

2.002 

14.32 

0.129 

I-7I3 

1.847 

14.28 

0.105 

1-395 

•512 

13-66 

4203.730 

0-143 

1.888 

2.O29 

14-52 

0.130 

I.72I 

1-855 

14-34 

0.106 

1.400 

•517 

13-70 

4209.144 

0.144 

1.896 

2.037 

14-57 

0.130 

1.719 

1-853 

14-32 

0.106 

1-399 

.516 

13-70 

4216.136 

0.142 

1.867 

2.008 

14-37 

0.129 

1.699 

1.834 

14.18 

0.104 

1-374 

.491 

13-47 

4220.509 

0.144 

1.892 

2-033 

14-54 

0.130 

I.7I2 

1.846 

14.27 

0.106 

1-397 

•514 

13-68 

4232.887 

0.143 

1.872 

2.013 

14.40 

0.130 

'•70S 

1.839 

14.22 

0.106 

i-39i 

.508 

13.62 

4257-815 

0.145 

1.897 

2.038 

14.58 

0.132 

1.714 

1.848 

14.28 

0.108 

1.404 

•521 

13-74 

4258.477 

0.143 

1-854 

1-995 

14.27 

0.130 

1.688 

1.822 

14.08 

0.108 

1-403 

.520 

-J3-73 

4265.418 

0.146 

1.887 

2.028 

14-51 

0.131 

1.697 

I.83I 

I4-I5 

0.108 

1-399 

.516 

I3-70 

4266.081 

0.146 

i.  880 

2.021 

14.46 

0.134 

1-734 

1.868 

14.44 

0.108 

•399 

.516 

13-70 

4268.915 

0.146 

1.879 

2.020 

14.45 

0.130 

1.682 

1.816 

14.04 

0.109 

.402 

•519 

I3-72 

4276.836 

0.145 

1.863 

2.OO4 

14-34 

0.131 

1.689 

1.823 

14.09 

0.108 

•390 

1-507 

13.61 

4284.838 

0.145 

i.  86  1 

2.OO2 

14.32 

0.131 

1.683 

1.817 

14.04 

O.IIO 

•415 

1-532 

13.84 

4287.566 

0.144 

1-855 

1.996 

14.28 

0.134 

1.721 

1-855 

14-34 

0.108 

-388 

I-505 

13.60 

4288.310 

0.144 

1.847 

1.988 

14.22 

0-133 

1.708 

1.842 

14.24 

O.IIO 

•413 

1-530 

13.82 

4290-377 

0.144 

1.847 

1.988 

14.22 

0.131 

1.681 

1.815 

14.03 

0.107 

-378 

1-495 

I3-5I 

4290.542 

0.146 

1.870 

2.OII 

14-39 

0.132 

1.694 

1.828 

I4-I3 

O.I  1  1 

•424 

I-54I 

13.92 

4291.630 

0.144 

1.849 

1-990 

14.24 

0.130 

1.667 

1.801 

13.92 

0.109 

-397 

I-SU 

13-68 

4294.936 

0.147 

i.  880 

2.  02  1 

14.46 

0.131 

1.679 

1.813 

14.01 

0.108 

-385 

1.502 

13-57 

<t>  =  54!" 

<*>  =  6g°.S 

<t>  =  77!8 

<t>  =  77:8* 

A 

V 

f  +  tij 

1 

A 

» 

»  +  », 

1 

A 

» 

f  +  »! 

£ 

A 

V 

»  +  », 

I 

km 

km 

0 

km 

km 

0 

km 

km 

0 

km 

km 

« 

4196.699 

0.068 

0.911 

I.OOI 

I2.0Q 

0.038 

0.527 

0.583 

|ll.82 

0.015 

0.232 

0.266 

8.94 

0.016 

0-253 

0.285 

9.64 

4197-257 

0.068 

0.911 

I.OOI 

I2.O9 

0.039 

0.541 

0-597 

I2.IO 

0.016 

0-245 

0-27? 

9-37 

0.017 

0-259 

0-293 

9.84 

4203.730 

0.069 

0.923 

I.OI5 

12.24 

0.040 

0-552 

0.608 

12-33 

0.019 

0.292 

0.326 

10.95 

0.021 

0.329 

0-363 

12.  2O 

4209.144 

0.071 

0.946 

1.036 

I2-5I 

0.040 

0-551 

0.607 

12.31 

0.018 

0.276 

0.310 

10.41 

O.O2O 

0.306 

0.340 

11.42 

4216.136 

0.067 

0.892 

0.982 

11.86 

0.038 

0.525 

0.581 

11.78 

0.017 

0.260 

0.294 

9.88 

O.OI7 

0.260 

0.294 

9.88 

4220.509 

0.069 

0.918 

i.  oof 

12.18 

0.040 

0-549 

0.605 

12.26 

0.017 

0.259 

0.295 

9.84 

0.021 

0.317 

0.351 

11.79 

4232.887 

0.070 

0.926 

.016 

12.27 

0.039 

0-533 

0.589 

11.94 

0.019 

0.288 

0.322 

10.82 

O.OI? 

0.264 

0.29? 

10.01 

4257-815 

0.072 

0-943 

•03: 

12.48 

0.042 

0.570 

0.626 

12.69 

O.O2I 

0.313 

0-34/ 

11.66 

O.OI9 

0.283 

0.313 

10.65 

4258.477 

0.069 

0.906 

o.ggf 

I2.O2 

0.041 

0-555 

0.611 

12.39 

O.OlS 

0.271 

0.305 

10.25 

0-023 

0-343 

0-373 

12.67 

4265.418 

0.071 

0.928 

.01  i 

!     12.30 

0.041 

0-554 

o.6ic 

12-37 

O.OlS 

0.270 

0.304 

IO.2I 

0.019 

0.282 

0.316 

10.62 

4266.081 

0.073 

0.952 

.04; 

12-59 

0.043 

0-577 

0.633 

12.83 

O.02I 

0-3I3 

0-347 

11.66 

O.O22 

0-325 

0-35? 

1  2.06 

4268.915 

0.070 

0.912 

.00; 

12.  II 

0.039 

0.527 

0-583 

11.82 

0.018 

0.270 

0.304 

IO.2I 

O.O2I 

0.322 

0-35? 

11.96 

4276.836 

0.070 

0.912 

.00: 

12.  II 

0.040 

0.538 

0-595 

1  2.O6 

O.O2O 

0.299 

0-333 

11.19 

0.022 

0.324 

0-35* 

12.03 

4284.838 

0.073 

0.948 

.03* 

!     12.54 

0.041 

o.SSi 

0.607 

12.30 

0.019 

0.283 

o.3i/ 

10.64 

O.O2O 

0.301 

0-33= 

11.25 

4287.566 

0.072 

0.936 

.026 

12.39 

0.042 

0.565 

0.619 

12-55 

0.018 

0.269 

0-303 

10.18 

O.OI9 

0.285 

0-31? 

10.72 

4288.310 

0.072 

0-935 

.02; 

12.38 

0.040 

0-537 

0.593 

12.  02 

0.019 

0.282 

0.316 

10.62 

0.019 

0.280 

0.314 

10.55 

4290.377 

0.073 

0.944 

•034 

[    12.49 

0.040 

0-537 

0-593 

1  2.  02 

0.019 

0.282 

0.316 

10.62 

O.O2O 

0.298 

0-33= 

11.15 

4290.542 

0.072 

0.932 

.02i 

12.35 

0.041 

0.548 

0.605 

12.26 

0.018 

0.268 

0.302 

10.15 

0.023 

0-345 

0-37? 

12.73 

4291.630 

0.068 

0.880 

0.97C 

>    11.71 

0.041 

0.548 

0.605 

12.26 

O.O2O 

0.297 

0.331 

II.  12 

0.022 

0-333 

0.365 

12.33 

4294.936 

0.072 

0.931 

1.021 

12-33 

0.044 

0.589 

0.640 

12.97 

0.018 

0.268 

0.302 

10.15 

O.OlS 

0.269 

0-30; 

10.18 

*  Measured  by  A.  on  G. 


4O    AN   INVESTIGATION   OF   THE   ROTATION   PERIOD    OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4. — RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  56.     1907,  Feb.  15,  6h  sm  G.  M.  T.     Measured  by  L.  on  T.    Distance  from  Limb  3.4  mm.    Quality,  good. 


p-f 

JT 

<t> 

•n 

seci) 

O       325.9 

19.4 

20.5 

69.S 

19.9 

1.064 

O-Q    251.5 

35-4 

36.0 

54-0 

11.7 

i.  02  1 

P         17-5 

Si-4 

51-7 

38-3 

8.8 

I.OI2 

D        -6.9 

67-4 

67.6 

22.4 

7-4 

1.008 

Diameter  174.0  mm 

82.4 

82.5 

I  7-5 

6.9 

1.007 

Factor        1.041 

*- 

f.S 

0  = 

22?4 

0= 

38!3 

X 

A 

t> 

.  +  ,, 

i 

A 

D 

.  +  + 

• 

A 

V 

.  +  ., 

1 

km 

km 

o 

km 

km 

• 

km 

km 

0 

4196.699 

0.141 

1.871 

2.012 

14.41 

0.127 

1.691 

1.825 

14.01 

0.098 

1-307 

1.422 

12.86 

4197-257 

0.142 

1.883 

2.024 

14.49 

0.128 

1.701 

1-835 

14.08 

0.098 

I-307 

1.422 

12.86 

4203.730 

0.143 

1.892 

2-033 

14.56 

0.131 

1-734 

1.868 

14-33 

0.102 

1-350 

I-465 

13-25 

4209.144 

0.143 

1.889 

2.030 

14-54 

0.131 

1.732 

1.866 

14-32 

O.IOI 

1-337 

1.452 

13.14 

4216.136 

0.142 

1.872 

2.013 

14.41 

0.128 

1.790 

1.824 

14.00 

O.IOO 

1-324 

1-439 

13.02 

4220.509 

0.143 

1.881 

2.O22 

14.48 

0.132 

1.732 

1.866 

14.32 

0.103 

1-359 

1-474 

13-34 

4232.887 

0.143 

1.858 

1.999 

14-31 

0.132 

1-730 

1.864 

14.30 

O.IO2 

1.341 

1.456 

13-17 

4257.815 

0.147 

1.907 

2.048 

14.67 

0.135 

1-749 

1.883 

14-45 

O.I  06 

1-374 

1.489 

13-47 

4258.477 

0.145 

1.881 

2.O22 

14.48 

0.132 

1.709 

1.843 

14.14 

O.I02 

1.329 

1.444 

13-07 

4265.418 

0.144 

1.862 

2.003 

14-34 

0.133 

1.721 

1-855 

14.23 

0.103 

1-335 

1-450 

13.12 

4266.081 

0.146 

1.888 

2.O29 

14-53 

0.135 

1.746 

i.  880 

14-43 

o.i  06 

1-372 

1.487 

13-45 

4268.915 

0.147 

1.898 

2.039 

14.60 

0.132 

I-703 

1-837 

14.10 

0.104 

I-346 

1.461 

13.22 

4276.836 

0.145 

1.868 

2.OO9 

14-39 

0.134 

1.727 

i.  86  1 

14.28 

0.104 

J-345 

1.460 

13.21 

4284.838 

0.146 

1.874 

2.015 

M-43 

0.133 

1.709 

1-843 

14.14 

0.103 

1.329 

1-444 

13-07 

4287.566 

0.146 

1-873 

2.014 

14-42 

0.133 

1.708 

1.842 

I4-I3 

0.104 

1.340 

1-455 

13.16 

4288.310 

0.144 

1.848 

1.989 

14.24 

0.133 

1.707 

1.841 

I4-I3 

0.104 

1-339 

1-454 

13.16 

4290.377 

O.I4S 

1.858 

1-999 

14-31 

0-133 

1.706 

1.840 

14.12 

0.104 

1.338 

1-453 

I3-I5 

4290.542 

0.145 

1.858 

1.999 

14-31 

0.134 

1.717 

1.851 

14.20 

0.105 

1-349 

1.464 

13-25 

4291.630 

0.144 

1.844 

1.985 

14.21 

0.133 

1.704 

1.838 

14.10 

0.103 

I-325 

1.440 

13-03 

4294.936 

0.146 

1.868 

2.009 

14-39 

0.134 

1.716 

1.850 

14.20 

0.104 

I-336 

I-45I 

13.13 

o 

0   = 

54.0 

0  = 

69!S 

4196.699 

0.067 

0.910 

.000 

12.08 

0.038 

0-533 

0.586 

11.88 

4197-257 

0.069 

0.932 

.022 

12.34 

0.038 

0-533 

0.586 

11.88 

4203.730 

0.072 

0.969 

•059 

12.79 

0.042 

0.587 

0.640 

12.97 

4209.144 

0.072 

0.966 

•056 

12.75 

0.042 

0.586 

0.639 

12.95 

4216.136 

0.068 

0.909 

0.999 

12.07 

0.038 

0-530 

0.583 

11.82 

4220.509 

0.071 

0.951 

.041 

12.57 

0.042 

0.582 

0.635 

12.87 

4232.887 

0.072 

0-959 

•049 

12.67 

0.041 

o.547 

0.600 

12.16 

4257-815 

0.074 

0.971 

.061 

12.82 

0.043 

0.588 

0.641 

12.99 

4258.477 

0.072 

0.947 

•037 

12.53 

0.041 

0.544 

0-597 

12.  IO 

4265.418 

0.072 

0.945 

•035 

12.50 

0.042 

0-573 

0.626 

12.69 

4266.081 

0.074 

0.969 

•059 

12.79 

0.044 

0.600 

0.653 

13.24 

4268.915 

0.072 

0.944 

•034 

12.49 

0.040 

0.542 

0-595 

12.  06 

4276.836 

0.073 

0.956 

.046 

12.63 

0.042 

0.568 

0.621 

12-59 

4284.838 

0.072 

0-943 

•033 

12.48 

0.041 

0-555 

0.608 

12-33 

4287.566 

0.074 

0.964 

•054 

12.73 

0.041 

0-554 

0.607 

12.31 

4288.310 

0.073 

0-953 

•043 

12.60 

0.041 

0-554 

0.607 

12.31 

4290.377 

0.071 

0.919 

.009 

12.19 

0.041 

0-554 

0.607 

12.31 

4290.542 

0.073 

0.952 

.042 

12.58 

0.041 

0-553 

0.606 

12.28 

4291.630 

0.074 

0.963 

•053 

12.72 

0.043 

0.580 

0-633 

12.83 

4294.936 

0.076 

0.986 

.076 

13.00 

0.041 

0-533 

0.586 

11.88 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1906-1907. 


TABLE  4. —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1906-1907  —  Continued. 
Plate  01  60.     1907,  Feb.  28,  7h  ism  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  3.0  mm.     Quality,  good. 


P-P 


sect; 


0-0 

f 

D 


339-1 

264.7 

21.4 

-7-2 


Diameter  173.2  mm 
Factor        1.036 


38.9 

39-5 

50-5 

11.4 

.020 

45-9 

46-3 

43-7 

IO.O 

.015 

54-7 

55-o 

35-0 

8.8 

.OI2 

6i.7 

61.9 

28.1 

8.2 

.010 

69-4 

69.6 

20.4 

7-7 

.009 

83-4 

83-5 

6.5 

7-4 

.008 

<t>  =  b°5 

<t>  =  6ts 

•t>  =  20°4 

A 

V 

»  +  », 

i 

A 

» 

»  +  », 

1 

A 

D 

»+  Jlj 

£ 

km 

km 

0 

km 

km 

0 

km 

km 

o 

4196.699 

0.144 

1.904 

2.044 

14.60 

0.143 

1.892 

2.032 

14-52 

0.128 

1.697 

1.830 

13-86 

4197-257 

0.144 

1.904 

2.044 

14.60 

0.144 

1.804 

2.044 

14.60 

0.130 

1.717 

1.850 

14.01 

4203.730 

0.146 

1.927 

2.067 

14.78 

0.146 

1.928 

2.068 

14.78 

0.130 

1.716 

1.849 

14.00 

4209.144 

0.147 

1.936 

2.076 

14-83 

0.145 

1.909 

2.049 

14.64 

0.131 

1.725 

1.858 

14.07 

4216.136 

0.146 

1.918 

2.058 

14.71 

0.146 

I-93I 

2.071 

14.79 

0.129 

1.697 

1.830 

13-86 

4220.509 

0.146 

I-9I5 

2-055 

14.68 

0.146 

1.929 

2.069 

14.78 

0.131 

1.719 

1.852 

14-03 

4232.887 

0.147 

1.919 

2.059 

14.71 

0.148 

1.932 

2.072 

14.80 

0.132 

1.724 

I-857 

14.06 

4257.815 

0.150 

1.940 

2.080 

14.86 

0.151 

I-95I 

2.091 

14.94 

0-133 

1.721 

1.854 

14.04 

4258.477 

0.148 

1.908 

2.048 

14.63 

0.147 

1.901 

2.041 

14-58 

0.132 

1.708 

1.841 

13-94 

4265.418 

0.147 

1.895 

2-035 

14-54 

0.148 

1.908 

2.048 

14.63 

0.131 

1.691 

1.824 

13.82 

4266.081 

0.147 

1.895 

2-035 

14-54 

0.150 

1-933 

2-073 

14.81 

0-135 

1-744 

1.877 

14.22 

4268.915 

0.148 

1.905 

2.045 

14.61 

0.149 

1.912 

2.052 

14.66 

0.133 

1.714 

1.847 

13-99 

4276.836 

0.146 

1-873 

2.013 

14.38 

0.149 

1.912 

2.052 

14.66 

0.132 

1.696 

1.829 

13-85 

4284.838 

0.149 

1.907 

2.047 

14.63 

0.146 

1.868 

2.008 

14-35 

0.134 

1.717 

1.850 

14.01 

4287.566 

0.149 

1.906 

2.046 

14.62 

0.149 

1.906 

2.046 

14.62 

0.131 

1.678 

1.811 

13-71 

4288.310 

0.149 

1.905 

2-045 

14.61 

0.147 

1.869 

2.009 

14-35 

0.132 

1.690 

1.823 

13.80 

4290.377 

0.147 

1.877 

2.017 

14.41 

0.146 

1.865 

2.005 

14.32 

0.134 

1-703 

1.836 

13-90 

4290.542 

0.147 

1.877 

2.017 

14.41 

0.149 

1.903 

2-043 

14-59 

0.132 

1.689 

1.822 

13.80 

4291.630 

0.146 

1.864 

2.004 

14-32 

0.148 

1.887 

2.027 

14.48 

0.133 

1.700 

I-833 

13.88 

4294.936 

0.148 

1.887 

2.027 

14.48 

0.148 

1.887 

2.027 

14.48 

0.134 

1.710 

1.843 

13.96 

<t>  =  28tl 

0  =  35to 

0  =  43?7 

<t>  =  s°!s 

A 

i) 

v  +  v1 

t 

A 

V 

v  +  i>i 

{ 

A    • 

r 

»  +  »! 

1 

A 

J 

»  +  I, 

£ 

km 

km 

0 

km 

km 

0 

km 

km 

0 

km 

km 

o 

4196.699 

0.114 

1.510 

1.636 

I3-I7 

0.104 

1.380 

1-497 

12.97 

0.086 

1.144 

.245 

12.24 

0.073 

0-977 

I.o6f 

11.92 

4197-257 

0.114 

1.510 

1.636 

I3-I7 

0.104 

1.380 

1.497 

12.97 

0.087 

1.158 

.261 

12.38 

0.074 

0.989 

i.oSc 

12.05 

4203.730 

0.118 

1.562 

1.67? 

I3-50 

0.106 

1.401 

I.SiS 

13.16 

0.088 

I.I68 

.271 

12.48 

0.075 

i.  002 

1.091 

12.  2O 

4209.144 

0.118 

J-557 

1.683 

13-55 

0.106 

.400 

I-5I7 

13-15 

0.089 

1.182 

.285 

12.62 

0.075 

1.  000 

1.091 

12.  l8 

4216.136 

0.114 

1.501 

I.62/ 

13.09 

0.105 

•384 

1.501 

13.01 

0.087 

1.152 

•255 

12.32 

0.074 

0.985 

1.076 

12.01 

4220.509 

O.I  20 

1-572 

1.69? 

I3-67 

0.107 

.406 

I-523 

13.20 

0.089 

1.  174 

•277 

12.54 

0.077 

1.  02  1 

1.  112 

12.41 

4232.887 

O.I  2O 

i-57o 

1.696 

I3-65 

0.107 

.401 

1-518 

13.16 

0.090 

1.182 

.285 

12.62 

0.076 

1.004 

1.095 

12.22 

4257.815 

O.I22 

1.580 

1.706 

'3-73 

o.  109 

-413 

•53° 

13-26 

0-093 

I.2IO 

•313 

12.89 

0.078 

1.020 

I.  Ill 

I2.4O 

4258.477 

O.I2I 

1-563 

1.685 

13-59 

0.108 

•397 

•5M 

13.12 

0.092 

I-I93 

•297 

12.74 

0.077 

1.008 

1.099 

12.27 

4265.418 

O.I  2O 

1-55° 

1.676 

13-49 

0.108 

•396 

.513 

13-" 

0.092 

I.I92 

•295 

12.72 

0.076 

0-993 

1.084 

12.  IO 

4266.081 

0.123 

1.582 

1.708 

13-75 

0.109 

•409 

.526 

13-23 

0.094 

I.22O 

•323 

12.99 

0.079 

1.029 

1.  120 

12.50 

4268.915 

0.120 

1.548 

I-674 

13-47 

0.108 

•395 

•5" 

13.10 

0.092 

1.189 

.292 

12.69 

0.077 

I.OO4 

1.095 

12.22 

4276.836 

O.I22 

1.568 

1.694 

I3-63 

O.I  10 

•4i5 

•532 

13.28 

0.091 

I.I76 

-279 

12.56 

0.076 

0.989 

I.OSO 

12.05 

4284.838 

O.I2I 

1-552 

1.678 

I3-50 

0.108 

.387 

1-504 

13.04 

0.093 

I.I97 

.300 

12.77 

0.078 

1.  01  1 

I.IO2 

12.30 

4287.566 

0.122 

1.566 

1.694 

13-63 

0.108 

1-387 

1.504 

13-04 

0.092 

1.186 

.289 

12.66 

0.076 

0.985 

I.O76 

12.01 

4288.310 

O.I2I 

1-552 

1.678 

I3-50 

0.109 

1.398 

I-5I5 

13-13 

0.092 

1.185 

1.288 

12.65 

0.078 

1.009 

I.IOO 

12.28 

4290.377 

O.I22 

1.564 

1.690 

13.60 

0.108 

1-385 

1.502 

13.02 

0.092 

1.184 

1.287 

12.64 

0.075 

0.972 

1.  06.5 

11.86 

4290.542 

O.I2I 

1-55° 

1.676 

13-49 

0.109 

1-397 

1-514 

13.12 

0.092 

1.182 

1.285 

12.62 

0.077 

0.996 

I.OS? 

12.13 

4291.630 

O.I22 

1.560 

1.686 

13-57 

0.108 

1.384 

1-501 

13.01 

0.093 

i-i93 

1.296 

12.73 

0.078 

1.008 

1.099 

12.27 

4294.936 

0.122 

1-559 

1.685 

I3-S6 

0.108 

1-383 

1.500 

13.00 

0.092 

1.181 

1.284 

1  2.6  1 

0.078 

1.007 

1.098 

12.26 

42     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  61.     1907,  Feb.  28,  7h  4Om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  3.1  mm.     Quality,  good. 


P-P 


sec  17 


o 

339-1 

23-7 

24.7 

65-3 

I7-S 

1.049 

o-n 

264.7 

29.7 

30.S 

59-5 

M-3 

1.032 

p 

21.4 

38-9 

39-S 

5°-5 

11.4 

1.  020 

D 

-7.2 

45-9 

46.3 

43-7 

IO.O 

1.016 

Diameter 

173.2  mm 

Factor 

i-°37 

p   i 

0  = 

43t7 

*- 

So!5 

*- 

S9°S 

*- 

59:5 

A 

V 

»  +  ., 

1 

A 

V 

V  +  Pj 

« 

A 

I) 

»  +  »! 

1 

A 

V 

,  +  ,, 

« 

km 

km 

• 

km 

km 

• 

km 

km 

0 

km 

km 

O 

4107  2^7 

*T  Ay  /  **o  / 

4203.730 

0.086 

1.  144 

.247 

12.25 

0.076 

1.015 

1.106 

12.34 

0.054 

0.730 

0.801 

II.  20 

0.056 

0-757 

0.828 

".58 

4209.144 

0.088 

1.148 

•251 

12.28 

0.077 

1.026 

1.117 

12.47 

0.058 

0.781 

0.852 

11.92 

0.055 

0.742 

0.813 

"•37 

4216.136 

0.085 

1.127 

.230 

12.08 

0.073 

0.971 

1.062 

11.85 

0.054 

0.728 

0.799 

11.18 

0-053 

0-7I3 

0.784 

10.97 

4220.509 

0.086 

I-I39 

.242 

12.20 

0.076 

1.009 

I.IOO 

12.28 

0.058 

0.779 

0.850 

11.89 

0-055 

0-739 

O.SlO 

"•33 

4232.887 

0.088 

1.158 

.261 

12.38 

0.076 

1.004 

1.095 

12.22 

0.056 

0.752 

0.823 

11.51 

0.056 

0-749 

0.820 

11.47 

4257.815 

0.090 

1.174 

.277 

12.54 

0.079 

1-034 

•125 

12.56 

0.060 

0.803 

0.874 

12.22 

0.060 

0.794 

0.865 

12.  IO 

4258.477 

0.089 

I.I57 

1.260 

12.37 

0.079 

1-033 

.124 

12.55 

0.057 

0-754 

0.825 

"•54 

0.058 

0.765 

0.836 

11.69 

0.077 

1.  001 

.006 

12.23 

0.058 

0.768 

0.839 

11.74 

0.060 

0.791 

0.862 

I  2.  06 

4266  081 

0.092 

1.196 

1.309 

12.85 

WJ 

:? 
.121 

12.11 

0.060 

O.702 

0.86-? 

12.07 

4268.015 

0.078 

1.015 

.106 

*  *••  0  * 
12.34 

0.059 

v.  /  y  * 
0.778 

"W"O 

0.849 

11.88 

0.060 

0.791 

0.862 

I  2.  06 

4276.836 

0.096 

1.163 

1.266 

12.43 

0.078 

1.013 

.IO4 

12.32 

0.057 

0.749 

0.820 

11.47 

0.058 

0.761 

0.832 

II.&4 

4284.838 

0.096 

1.161 

1.264 

12.41 

0.079 

1.024 

•"5 

12.44 

0.058 

O.760 

0-831 

11.62 

0.058 

0.760 

0.831 

11.62 

4287.566 

0.092 

1.186 

1.289 

12.66 

0.079 

1.023 

.114 

12.43 

0.057 

0.746 

0.817 

"•43 

0.058 

0.760 

0.831 

11.62 

4288.310 

0.091 

I-I75 

1.278 

12.55 

0.079 

1.022 

•"3 

12.42 

0.060 

0.785 

0.856 

11.97 

0.059 

0-773 

0.844 

II.80 

4290.377 

0.091 

I-I73 

1.276 

12.53 

0.077 

0-995 

.086 

12.12 

0.059 

0.772 

0.843 

11.79 

0.059 

0-773 

0.844 

II.SO 

4290.542 

0.090 

I-I59 

1.262 

12.39 

0.080 

1.034 

-125 

12.56 

0.058 

0.760 

0.831 

11.62 

0.060 

0.784 

0.855 

11.96 

4291.630 

0.091 

1.172 

1-275 

12.52 

0.078 

1.008 

.099 

12.2? 

0.058 

0.758 

0.829 

1  1.  60 

0.060 

0.784 

0.855 

11.96 

4294.936 

0.090 

I-I57 

1.260 

12.37 

0.077 

0-994 

.085 

12.  II 

0.059 

0.771 

0.842 

11.78 

0.058 

0.758 

0.829 

1  1.  60 

*- 

65^3 

,- 

as:3 

</>   = 

*,' 

*- 

«*' 

A  1  06  6oO 

t^L  \J\t.\J\J\f 

4.IO7  2S7 

f-y  /  •*  j  / 

4203.730 

0.044 

0.605 

0.664 

11.28 

0.045 

0.618 

0.677 

11.50 

0.046 

0.633 

0.692 

"•75 

0.047 

0.652 

0.711 

I  2.  08 

4209.144 

0.045 

0.617 

0.676 

11.49 

0.045 

0.617 

0.676 

11.49 

0.047 

0.676 

0-735 

12.49 

0.047 

0.640 

0.699 

11.88 

4216.136 

0-043 

0.587 

0.646 

10.98 

0.043 

0.587 

0.646 

10.98 

0.048 

0.652 

0.711 

12.08 

0.045 

0.621 

0.68o 

"•55 

4220.509 

0.044 

0.602 

0.661 

11.23 

0.044 

0.600 

0.659 

11.19 

0.047 

0.645 

0.704 

11.96 

0.047 

0.642 

O.7OI 

11.91 

4232.887 

0.045 

0.611 

0.670 

"•38 

0.047 

0.638 

0.697 

11.84 

0.050 

0.669 

0.728 

12.37 

0.049 

0.669 

0.728 

12.37 

4257-815 

0.048 

0.646 

0.705 

11.98 

0.048 

0.646 

0.705 

11.98 

0.049 

0.659 

0.718 

12.  2O 

0.045 

0.636 

0-695 

11.81 

4258.47? 

0.046 

0.619 

0.678 

11.52 

0.047 

0.631 

0.690 

11.72 

0.051 

0.684 

0-743 

12.62 

0.050 

0.673 

0.732 

12.44 

4265.418 

0.046 

0.618 

0.677 

11.50 

0.045 

0.604 

0.663 

11.26 

0.047 

0.629 

0.688 

11.69 

0.051 

0.685 

0-744 

12.64 

4266.081 

0.048 

0.644 

0.703 

11.94 

0.048 

0.643 

0.702 

11.93 

0.051 

0.687 

0.746 

12.67 

0.048 

0.645 

0.704 

11.96 

4268.915 

0.048 

0.643 

0.702 

11.93 

0.052 

0.698 

0-757 

12.86 

0.054 

0.719 

0.778 

13.22 

4276.836 

0.045 

0.602 

0.661 

11.23 

0.046 

0.615 

0.674 

"-45 

0.05  T 

0.680 

0-739 

12.56 

0.050 

0.672 

0.731 

12.42 

4284.838 

0.046 

0.614 

0.673 

"•43 

0.047 

0.626 

0.685 

11.64 

0.052 

^694 

0-753 

12.79 

0-053 

0.712 

0.771 

13.10 

4287.566 

0.047 

0.625 

0.684 

11.62 

0.047 

0.625 

0.684 

11.62 

0.049 

0.656 

0-715 

12.15 

0.052 

0.687 

0.746 

12.67 

4288.310 

0.047 

0.625 

0.684 

11.62 

0.047 

0.626 

0.685 

11.64 

O.O49 

0-653 

0.712 

12.  IO 

0.049 

0.656 

0.7IS 

12.15 

4290.377 

0.048 

0.638 

0.697 

11.84 

0.047 

0.625 

0.684 

11.62 

O.048 

0.645 

0.704 

11.96 

0.051 

0.682 

0.741 

12.59 

4290.542 

0.045 

0.598 

0.657 

ii.  16 

0.046 

0.612 

0.671 

11.40 

0.049 

0.650 

0.709 

I2.O5 

0.049 

0.650 

0.709 

12.05 

4291.630 

0.047 

0.624 

0.683 

1  1.  60 

0.046 

0.611 

0.670 

".38 

O.O52 

0.697 

0.756 

12.84 

0.049 

0.650 

0.709 

12.05 

4294.936 

0.048 

0.637 

0.696 

11.82 

0.046 

0.610 

0.669 

"•37 

0.050 

0.668 

0.727 

I2-35 

0.048 

0.639 

0.698 

11.86 

*  Measured  by  A.  on  G. 


RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


43 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1906-1907  —  Continued. 
Plate  to  62.     1907,  Feb.  28,  gh  15™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  3.1  mm.     Quality,  good. 


seci) 


O      339-1 

o-n   264.7 

p       21.4 

D       -7.2 

Diameter  173.2  mm 

Factor        1.037 


51.  5 

5J-9 

38.1 

9-2 

1.013 

59-5 

59-8 

30.2 

8.4 

i.  on 

67-3 

67-S 

22.5 

7-8 

1.009 

74-3 

74-4 

15-6 

7-5 

i.oog 

82.0 

82.1 

7-9 

7-3 

1.008 

96.0 

96.0 

-6.0 

7-3 

1.008 

0  = 

—  6to 

<t>  = 

?!o 

0  = 

i$'6 

A 

V 

r  +  », 

J 

A 

V 

»  +  »! 

& 

A 

V 

»  +  », 

1 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.144 

1.905 

2.045 

14.60 

0.138 

1.831 

I.Q7I 

14.13 

0.138 

1.829 

1.965 

14.48 

4I97-257 

0.144 

I.905 

2.045 

14.60 

0.139 

1.842 

1.982 

14.21 

0.139 

1.840 

1.976 

14.57 

4203.730 

0.145 

1.914 

2.054 

14.66 

0.142 

1.  880 

2.O2O 

14.48 

0.142 

1-875 

2.01  1 

1482 

4209.144 

0.146 

1-923 

2-063 

14.72 

0.142 

1.877 

2.017 

14.46 

0.142 

1.872 

2.008 

1480 

4216.136 

0.144 

1.891 

2.031 

14.50 

0.141 

1.854 

1.994 

14.29 

0.141 

I.854 

1.990 

I4'6? 

4220.509 

0.147 

1.926 

2.066 

14.74 

0.142 

1.864 

2.OO4 

14.36 

0.142 

1.864 

2.000 

14-74 

4232-887 

0.148 

I-93I 

2.071 

14.78 

0.144 

1.879 

2.OI9 

14.47 

0.144 

1.880 

2.Ol6 

14.86 

4257.815 

0.150 

1.938 

2.078 

14.83 

0.147 

1.897 

2.037 

14.60 

0.147 

1.900 

2.036 

15.01 

4258.47? 

0.146 

1.887 

2.027 

14.47 

0.146 

1.874 

2.OI4 

14.44 

0.144 

1.872 

2.008 

14.80 

4265.418 

0.147 

1.895 

2.035 

14.52 

0.144 

1.869 

2.OO9 

14.40 

0.144 

1.867 

2.003 

14  76 

4266.081 

0.150 

1-933 

2.073 

14.80 

0.144 

1.868 

2.008 

14-39 

0.144 

1.866 

2.OO2 

14.76 

4268.915 

0.147 

i.88g 

2.029 

14.48 

0.144 

1.867 

2.OO7 

14-38 

0.144 

1.865 

2.001 

14-75 

4276.836 

0.147 

1.887 

2.027 

14.47 

0.145 

1.864 

2.OO4 

14.36 

0.145 

1.862 

1.998 

14-73 

4284.838 

0.148 

1.894 

2-034 

14-52 

0.144 

1.830 

1.970 

14.12 

0.144 

1.845 

I.gSl 

14.60 

4287.566 

0.146 

1.868 

2.008 

14-33 

0.143 

1.825 

1.965 

14.08 

0.143 

1.830 

1.966 

14.47 

4288.310 

0.150 

1.917 

2.057 

14.68 

0.144 

1.844 

1.984 

14.22 

0.144 

1.842 

1.978 

14.58 

4290.377 

0.148 

1.890 

2.030 

14.49 

0.143 

1.830 

1.970 

14.12 

0.142 

1.828 

1.964 

14.48 

4290.542 

0.148 

1.890 

2.030 

14.49 

0.144 

1.842 

1.982 

14.21 

0.144 

1.840 

1.976 

14-57 

4291.630 

0.146 

1.865 

2-005 

14-31 

0.145 

1.853 

1-993 

14.28 

0.145 

1.851 

1.987 

14.65 

4294.936 

0.148 

1.887 

2.027 

14.47 

0.145 

1.859 

1.999 

14.33 

0.145 

1.857 

1-993 

14.69 

<t>  = 

2* 

<t>  = 

30^2 

0  = 

38*1 

4196.699 

0.124 

1.644 

1-775 

13.64 

0.115 

i-Si? 

1.641 

13.48 

0.105 

1.396 

•S09 

13.61 

4197-257 

0.123 

1.628 

1-759 

13-52 

0.116 

1.529 

1-653 

13.58 

0.105 

1.396 

•509 

13.61 

4203.730 

0.126 

1.664 

J-795 

13-79 

0.118 

1.548 

1.672 

13-73 

0.107 

I.4I5 

-528 

13-79 

4209.144 

0.127 

1-673 

1.804 

13.86 

0.118 

1-547 

1.671 

13.73 

0.107 

I-4I3 

-526 

13-77 

4216.136 

0.125 

1.645 

1.776 

13.65 

0.116 

1-527 

1.651 

13.55 

0.106 

1-399 

•512 

13.64 

4220.509 

0.126 

1-655 

1.786 

13-72 

0.118 

1-544 

1.668 

13.70 

0.107 

1.409 

.522 

13-73 

4232.887 

0.128 

1.672 

1.803 

13.85 

0.118 

1-543 

1.667 

13.69 

0.106 

i-39' 

•504 

13-57 

4257-815 

0.131 

1.694 

1.825 

14.02 

O.I  2O 

1-554 

1.678 

13-78 

O.IIO 

1.428 

•541 

13.90 

4258.477 

0.130 

1.681 

1.  812 

13-92 

0.119 

I-54I 

1-665 

13-68 

0.108 

1.402 

•5iS 

13-67 

4265.418 

0.128 

1.650 

1.781 

13.69 

0.118 

1.521 

1.645 

13.51 

0.108 

1.400 

I-SI3 

13-65 

4266.081 

0.130 

1.676 

1.807 

13.89 

O.I  2O 

1-549 

1-673 

13.74 

O.IIO 

1.424 

1-537 

13-87 

4268.915 

0.130 

1-675 

i.  806 

13-88 

0.118 

1-518 

1.642 

13.49 

0.108 

1.389 

1.502 

13-55 

4276.836 

0.129 

1.656 

1.787 

I3-7V 

0.118 

1-518 

1.642 

13.49 

0.108 

1.389 

.502 

13-55 

4284.838 

0.131 

1.678 

1.809 

i   .90 

0.116 

1.490 

1.614 

13.26 

0.107 

1-378 

.491 

13-45 

4287.566 

0.130 

1.662 

1-793 

13-78 

0.117 

1.501 

1.625 

13.35 

0.108 

1-388 

.501 

13-54 

4288.310 

0.129 

1.649 

1.780 

13-68 

0.122 

1.560 

1.684 

13.83 

0.108 

1.388 

.501 

13-54 

4290.377 

0.130 

i.  660 

1.791 

I3-76 

O.II8 

1.511 

1-635 

13-43 

0.107 

1-375 

.488 

I3-42 

4290.542 

0.127 

1.623 

J-754 

13-48 

O.I  2O 

1-535 

1.659 

13-63 

0.108 

1-387 

.500 

13-53 

4291.630 

0.128 

1-634 

1-765 

I3-S6 

O.I  20 

1-534 

1-658 

13.62 

0.109 

1-397 

.510 

13.62 

4294.936 

0.128 

1-633 

1.764 

13-56 

O.I  2O 

1-533 

1-657 

13.61 

O.IIO 

1.409 

.522 

'3.73 

44    AN   INVESTIGATION   OF   THE   ROTATION   PERIOD    OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907 — -Continued. 
Plate  w  63.     1907,  Feb.  28,  9h  45"™  G.  M.  T.    Measured  by  L.  on  T.     Distance  from  Limb  3.1  mm.    Quality,  good. 


t-P 


secy 


Q       339.1 

45-8 

46.2 

43-8 

IO.O 

1.016 

O-n    264.7 

38.8 

39-3 

S°-7 

"•5 

i.  02  1 

p       21.4 

54-6 

54-9 

3S-I 

8.8 

I.OI2 

D       -7.2 

61.6 

61.8 

28.2 

8.2 

I.OIO 

Diameter  173.2  mm 

69-3 

69.4 

20.6 

7-7 

1.009 

Factor        1.037 

82.8 

82.8 

7.2 

7-3 

1.008 

<t>  = 

?:* 

0  = 

2O?6 

0  = 

aSta 

X 

A 

V 

v  +  vl 

e 

A 

» 

"  +  fj 

e 

A 

r 

»  +  », 

{ 

km 

km 

0 

km 

km 

0 

km 

km 

. 

4196.699 

0.143 

i-9°5 

2.045 

14-63 

0.126 

1.668 

1.801 

13.66 

0.114 

.510 

1.636 

13.18 

4197-257 

0.144 

1.918 

2.058 

14-73 

0.128 

1.694 

1.827 

13.86 

0.116 

•536 

1.662 

13.39 

4203.730 

0.147 

•953 

2.093 

14.98 

O.I  2O 

1.  600 

1-733 

13.14 

0.118 

.560 

1.686 

13.58 

4209.144 

0.142 

.885 

2.025 

14.49 

0.129 

1.700 

1-833 

13.90 

o.i  19 

•570 

1.696 

13.66 

4216.136 

0.144 

•9°5 

2.045 

14.63 

0.130 

1.708 

1.841 

13.96 

0.118 

•553 

1.679 

13.53 

4220.509 

0.144 

.902 

2.042 

14.61 

0.132 

•730 

1-863 

14.13 

O.I  2O 

•575 

1.701 

13.70 

4232.887 

0.146 

.920 

2.060 

14.74 

0.133 

.736 

1.869 

14.18 

O.I  2O 

•569 

1-695 

13-65 

4257-815 

0.150 

•953 

2.093 

14.98 

0.133 

.719 

1.852 

14.05 

O.I  2O 

•555 

i.  68  1 

13.54 

4258.477 

0.148 

.927 

2.067 

14.79 

0-133 

.719 

1.852 

14.05 

0.118 

•526 

1.652 

13-31 

4265.418 

0.147 

.896 

2.036 

14.57 

0.132 

.702 

1.835 

13.92 

0.118 

•524 

1.650 

13.29 

4266.081 

0.150 

•947 

2.087 

14-93 

0-133 

•715 

1.848 

14.02 

0.124 

.602 

1.728 

13.92 

4268.915 

0.146 

.894 

2.034 

14.55 

0.134 

.725 

1.858 

14.09 

0.120 

•545 

1.671 

13.46 

4276.836 

0.147 

.901 

2.041 

14.61 

0-133 

1.708 

1.841 

13.96 

O.I  2O 

•542 

1.668 

13.44 

4284.838 

0.149 

.921 

2.001 

14-75 

0.134 

1.716 

1.849 

14.02 

0.123 

•579 

1-705 

13.73 

4287.566 

0.148 

.906 

2.046 

14.64 

0.136 

1.738 

1.871 

14.19 

O.I2I 

•549 

1-675 

13.49 

4288.310 

0.146 

.881 

2.O2I 

14.46 

0.134 

I.7I3 

1.846 

14.00 

0.124 

.588 

1.714 

13.81 

4290.377 

0.147 

.892 

2.032 

14-54 

0.134 

1.712 

1.845 

13.99 

O.IlS 

.510 

1.636 

13.18 

4290.542 

0.148 

•9°3 

2.043 

14.62 

0.135 

1.724 

1.857 

14.08 

O.I  2O 

1-535 

1.661 

13.38 

4291.630 

0.148 

1.902 

2.O42 

14.61 

0.134 

1.7X1 

1.844 

13.99 

0.119 

1.522 

1.648 

13.28 

4294.936 

0.148 

1.901 

2.O4I 

14.61 

0.132 

1.685 

1.818 

13.79 

0.118 

1.508 

1.634 

13.16 

0  = 

35!i 

0  = 

sot? 

0  = 

43:« 

4196.699 

0.105 

1.396 

•513 

13-13 

0.068 

0.912 

1.002 

11.23 

0.086 

1.150 

1.254 

12.33 

4197.257 

o.i  06 

1.409 

.526 

13-25 

0.069 

0.924 

I.OI4 

11.36 

0.088 

1.174 

1.278 

12.57 

4203.730 

0.108 

i-43i 

•548 

13-44 

0.072 

0.962 

1.052 

11.79 

0.090 

•199 

•303 

12.82 

4209.144 

0.108 

1.428 

•545 

13.40 

0.071 

0.948 

1.038 

11.63 

0.089 

.181 

.285 

12.64 

4216.136 

o.i  06 

1-399 

.516 

13.16 

0.071 

0.945 

•035 

1  1.  60 

0.087 

•152 

.256 

12.35 

4220.509 

O.IIO 

1-447 

.564 

13-57 

0.073 

0.971 

.061 

11.89 

0.090 

.188 

.292 

12.71 

4232.887 

0.108 

1.412 

•529 

13-27 

0.071 

0-939 

.029 

"•53 

0.090 

.183 

.287 

12.66 

4257.815 

O.I  II 

1.440 

•557 

13-51 

0.076 

O.Q95 

.085 

12.16 

0.094 

.224 

.328 

13.06 

4258.477 

0.108 

1-399 

.516 

13.16 

0.075 

0.982 

.072 

12.  02 

0.090 

.172 

.276 

12.55 

4265.418 

0.107 

1-385 

1.502 

13-03 

0.075 

0.982 

.072 

I  2.  02 

0.089 

•157 

.261 

12.40 

4266.081 

O.II2 

1.449 

1.566 

13-59 

0-075 

0.984 

.074 

I2.O4 

0.092 

.194 

.298 

12.77 

4268.915 

O.IIO 

1.422 

1-539 

13-36 

0.076 

0.989 

.079 

12.09 

0.091 

.180 

.284 

12.63 

4276.836 

0.108 

1-394 

1.511 

13.11 

0.076 

0.988 

.078 

I  2.08 

0.090 

.165 

.269 

12.48 

4284.838 

O.IIO 

I.4I5 

1-532 

13.29 

0.078 

I.OI2 

.IO2 

12-35 

0.092 

.186 

.290 

12.69 

4287.566 

O.IIO 

I-4I3 

1-53° 

13.28 

0.074 

0-959 

.049 

11.76 

0.092 

.185 

1.289 

12.68 

4288.310 

O.I  12 

1-437 

1-554 

13.48 

0.074 

0.958 

.048 

"•75 

0.090 

.160 

1.264 

12.43 

4290.377 

0.108 

1-387 

1.504 

13-05 

0.076 

0.983 

•073 

12.03 

0.091 

.171 

1-275 

12.54 

4290.542 

O.III 

1.424 

I-54I 

13-37 

0.074 

9-957 

•047 

11.74 

0.093 

.196 

1.300 

12.79 

4291.630 

O.I  1  2 

1-435 

1-552 

13-47 

0.076 

0.982 

.072 

12.02 

0.092 

.182 

1.286 

12.65 

4294.936 

O.II2 

1-434 

I-55I 

13-46 

0.077 

0-995 

.085 

12.  l6 

0.092 

.182 

1.286 

12.65 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 

TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 

Plate  o>  55.     1907,  Feb.  15,  sh  40'"  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  3.4  mm.     Quality,  good. 

p— P          T  (j>  i)          seci; 


45 


G       325.9 

O-fi     251.5 

P         17.5 


Si-4 
67.4 
82.4 


Si-7 
67.6 
82.5 


38.3 
22.4 

7-5 


8.8 

7-4 
6.9 


I.OI2 
1.008 
1.007 


D     -6.9 

Diameter  174.0  mm 
Factor        1.041 


X 

0  =  7°.S 

<t>  =  «?4 

*  =  3&°.3 

A 

fl 

»  +  "l 

« 

A 

V 

»  +  »! 

£ 

A 

V 

»  +  »! 

{ 

km 

km 

O 

km 

km 

0 

km 

km 

9 

4196.699 

0.142 

1.884 

2.025 

14.50 

0.129 

1.711 

1.845 

14.16 

0.098 

1.304 

1.419 

12.84 

4197-257 

0.142 

1.884 

2.025 

14-50 

0.129 

1.711 

1-845 

14.16 

0.097 

1.292 

1.407 

12.73 

4203.730 

0.146 

1.924 

2.065 

14.79 

0.130 

1.721 

1-855 

14-23 

0.102 

1-354 

1.469 

13.29 

4209.144 

0.147 

1.936 

2.077 

14.87 

0.131 

1-730 

1.864 

14-30 

0.103 

1.364 

1-479 

I3-38 

4216.136 

0-145 

1.910 

2.051 

14.69 

0.129 

1.699 

1.833 

14.07 

0.099 

I-3I4 

1.429 

12.93 

4220.509 

0.146 

1.918 

2.059 

14-74 

0.131 

I-723 

1-857 

14-25 

0.103 

1.361 

1.476 

13-35 

4232.887 

0.147 

1.924 

2.065 

M-79 

0.132 

1.728 

1.862 

14.28 

0.104 

1.368 

1.483 

I3-42 

4257-815 

0.149 

1.923 

2.064 

14.78 

0.135 

1.741 

1-875 

14-39 

0.106 

1-378 

1-493 

I3-5I 

4258.477 

0.146 

1.898 

2.039 

14.60 

0.131 

1.696 

1.830 

14.04 

0.105 

'•365 

1.480 

13-39 

4265.418 

0.148 

1.919 

2.060 

14-75 

0.131 

1.695 

1.829 

14-03 

0.104 

J-352 

1.467 

I3-27 

4266.081 

0.151 

1-953 

2.094 

14.99 

0.135 

1.738 

1.872 

14-37 

0.108 

1-395 

1.510 

13.66 

4268.915 

0.149 

1.918 

2.059 

14.74 

0.134 

I-725 

1.859 

14.27 

0.104 

1-347 

1.462 

I3-23 

4276.836 

0.148 

1.903 

2.044 

14.64 

0.132 

1.700 

1.834 

14.07 

0.103 

1-334 

1.449 

13.11 

4284.838 

0.149 

i-9i3 

2-054 

14.71 

0.134 

1.722 

1.856 

14.24 

0.104 

1-342 

1-457 

13-18 

4287.566 

0.147 

1.885 

2.026 

I4-5I 

0.133 

1.709 

1-843 

14.14 

0.104 

i-34i 

I-456 

I3-I7 

4288.310 

0.149 

1.910 

2.051 

14.69 

0.133 

1.708 

1.842 

14-13 

0.106 

1-365 

1.480 

13-39 

4290-377 

0.146 

1.871 

2.OI2 

14.41 

0.133 

1.707 

1.841 

14-13 

0.105 

1-352 

1.467 

I3-27 

4290.542 

0.148 

1.896 

2.037 

14-59 

0.134 

I-7I5 

1.849 

14-19 

O.IO2 

I.3IS 

1.430 

12.94 

4291.630 

0.148 

1.895 

2.036 

14.58 

0-134 

1.714 

1.848 

14.18 

0.105 

1-350 

1.465 

13.25 

4294.936 

0.148 

1.894 

2.035 

14-57 

0.131 

1.678 

1.812 

13.90 

0.108 

1-387 

1.502 

13-59 

Plates  <•>  64,  w  67,  w  68,  and  a  69.      1907,  April  7,  w  64,  3h  2om  ;    u  67,  5h  45m  ;    w  68,  6h  45™  ;   w  69,  7h  iom.     G.  M.  T.     Measured 

by  L.  on  T.     Distance  from  Limb  2.3  mm.     Quality,  good. 


w  64,167 

u  68,  69 

O 
0-0 

i6?7 
302.3 

i6?8 
302.4 

p 

D 

26.5 
-6.1 

p-p 

O 

10.9 


77S 


*) 
29-5 


seci 
1.149 


Diameter    171.7  mm 
Factor          1.027 


X 

u  64,  0  =  77?s 

w  67,  0  =  77?s 

<•>  68,  <f  =  77°5 

w  <>9,  <t>  =  7?!s 

A 

t> 

V  +  "] 

£ 

A 

» 

V  -f-  »j 

« 

A 

» 

f  +  », 

i 

A 

V 

»+  »! 

f 

km 

km 

. 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

O.O2O 

0.298 

0-333 

10.92 

0.018 

0.269 

0-304 

9-97 

0.018 

0.269 

0-304 

9-97 

O.O2O 

0.298 

0-333 

10.92 

4197-257 

0.022 

0-304 

0-339 

II.  12 

0.020 

0.298 

0-333 

10.92 

O.O2O 

0.298 

0-333 

10.92 

O.O2O 

0.298 

0-333 

10.92 

4203.730 

0.023 

0.342 

0-377 

12-37 

O.O22 

0.327 

0.362 

11.87 

0.022 

0.328 

0.363 

11.91 

0.022 

0.328 

0-363 

11.91 

4209.144 

O.O22 

0-303 

0-338 

II.O9 

O.O22 

0.327 

0.362 

11.87 

O.O22 

0-328 

0.363 

11.91 

O.O2I 

0.312 

0-347 

11.38 

4216.136 

0.020 

0-295 

0-330 

10.82 

O.OI9 

0.282 

0.317 

10.40 

O.OI9 

0.282 

0.317 

10.40 

O.O2O 

0.296 

0-33' 

10.86 

4220.509 

O.O22 

0.324 

0-359 

11.78 

O.O22 

0.325 

0.360 

11.81 

O.O22 

0.326 

0.361 

11.84 

0.024 

0-355 

0-390 

12.79 

4232.887 

O.O22 

0.324 

0-359 

11.78 

O.O22 

0.324 

0-359 

11.78 

O.O22 

0-323 

0.358 

11.74 

O.O24 

0-351 

0.386 

12.66 

4257-815 

0.024 

0-349 

0.384 

I  2.6O 

0.026 

0.380 

0-415 

13-61 

O.O26 

0-380 

0-415 

13.61 

0.028 

0.408 

0-443 

14-53 

4258.477 

O.O24 

0-349 

0.384 

I  2.  60 

O.022 

0.323 

0.358 

11.74 

O.024 

0-349 

0.384 

12.60 

O.O24 

0-349 

0.384 

12.60 

4265.418 

O.O24 

0.349 

0.384 

1  2.  60 

0.023 

0-335 

0.370 

12.14 

O.O22 

0.322 

0-357 

11.71 

O.O22 

0-320 

0-355 

11.64 

4266.081 

0.025 

0-363 

0-398 

13.06 

0.026 

0-379 

0.414 

I3-58 

0.025 

0.363 

0.398 

13.06 

O.O24 

0-349 

0.384 

12.60 

4268.915 

0.023 

0-334 

0.369 

12.  IO 

O.O24 

0-347 

0.382 

12-53 

0.023 

0-334 

0-369 

12.10 

O.O22 

0.320 

0.355 

11.64 

4276.836 

O.O22 

0.319 

0-354 

II.6l 

O.O24 

0-347 

0.382 

12-53 

O.O24 

0.348 

0-383 

12.56 

O.O24 

0.348 

0-383 

12.56 

4284.838 

O.O22 

0.319 

0-354 

11.61 

O.O24 

0-347 

0.382 

12-53 

O.024 

0.348 

0.383 

12.56 

O.O22 

0.320 

0-355 

11.64 

4287.566 

O.O2I 

0-303 

0-338 

11.09 

0.025 

0.361 

0.396 

12-99 

O.O22 

0.317 

0-352 

"•55 

O.O24 

0-347 

0.382 

12.53 

4288.310 

O.O22 

0.318 

0-353 

11.58 

O.O24 

0-347 

0.382 

12.53 

0.023 

0.332 

0.367 

12.04 

O.O24 

0-347 

0-382 

12.53 

4290.377 

0.025 

0.361 

0.396 

12.99 

O.O22 

0.3I7 

0.352 

ii-SS 

0.024 

0-347 

0.382 

12-53 

O.022 

0.319 

0-354 

11.61 

4290.542 

0.023 

0.332 

0.367 

12.04 

0.023 

0.332 

0.367 

12.04 

O.O26 

0-374 

0.409 

13-42 

O.O24 

0.346 

0.381 

12.50 

4291.630 

0.025 

0.360 

0-395 

12.96 

O.O28 

0.404 

0-439 

14.40 

O.O25 

0.360 

0-395 

12.96 

O.O24 

0.346 

0.381 

12.50 

4294.936 

O.O22 

0.317 

0.352 

ii-SS 

0.024 

0.346 

0.381 

12.50 

0.024 

0.346 

0.381 

12.50 

0.023 

0-332 

0.367 

12.04 

46     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 

TABLE  4. —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 

Plate  u>  81.     1907,  April  22,  8h  2om  G.  M.  T.     <t>  =  79!$,  measured  by  A.  on  T.     <t>  =  67^2  and  72°$  measured  by  L.  on  T.    Distance 

from  Limb  i.i  mm.    Quality,  good. 


P-P 


sec  i? 


3I.S 

G-0    317.1 

P        25.7 

D       -4.9 

Diameter  169.3  mm 

Factor        1.013 


9.3  10.5  79.5  28.1  1.134 
16. 8  17.5  72.5  16.6  1.044 
22.3  22.8  67.2  12.8  1.026 


X 

,  =  6* 

*  =  67!, 

*-7* 

A 

V 

'  +  »' 

1 

A 

t) 

'+'' 

1 

A 

V 

'  +  '' 

i 

km 

km 

0 

km 

km 

• 

km 

km 

o 

4196.699 

0.042 

0-553 

0.617 

11.30 

0.041 

0.541 

0.605 

11.08 

0.032 

0.429 

0.480 

"•33 

4197-257 

0.042 

0-553 

0.617 

11.30 

0.042 

0-553 

0.617 

11.30 

0.033 

0.441 

0.492 

11.62 

4203.730 

0-043 

0.564 

0.628 

11.51 

0.044 

0-577 

0.641 

11.74 

0.034 

0-454 

0.505 

11.92 

4209.144 

0.045 

0.588 

0.652 

"•95 

0.045 

0.588 

0.652 

"•95 

0.034 

0-453 

0.504 

11.90 

4216.136 

0.044 

0-575 

0.639 

11.71 

0.040 

0-523 

0.587 

10.75 

0.033 

0-439 

0.490 

"•57 

4220.509 

0.044 

0.572 

0.636 

11.65 

0.044 

0-574 

0.638 

11.69 

0.034 

0.451 

0.502 

11.85 

4232.887 

0.046 

0.596 

0.66o 

12.09 

0.048 

0.617 

0.681 

12.48 

0.035 

0-459 

0.510 

12.04 

4257-815 

0.049 

0.628 

0.692 

12.68 

0.048 

0.615 

0.679 

12.44 

0.036 

0.470 

0.521 

12.30 

4258.477 

0.048 

0.615 

0.679 

12.44 

0.045 

0-577 

0.641 

11.74 

0.034 

0-444 

0-495 

11.69 

4265.  4X8 

0.046 

0.590 

0.654 

11.98 

0.046 

0.590 

0.654 

11.98 

0.034 

0.444 

0-495 

11.69 

4266.081 

0.050 

0.638 

0.702 

12.86 

0.048 

0.613 

0.677 

12.40 

0.037 

0.482 

0-533 

12.58 

4268.915 

0.047 

0.600 

0.664 

12.  l6 

0.046 

0.587 

0.651 

"•93 

0.033 

0.430 

0.481 

11.36 

4276.836 

0.048 

0.613 

0.677 

12.40 

0.045 

0-575 

0.639 

11.71 

0.036 

0.465 

0.516 

12.  18 

4284.838 

0.044 

0-559 

0.623 

11.41 

0.047 

0.598 

0.662 

12.13 

0.034 

0.440 

0.591 

"•59 

4287.566 

0.048 

0.610 

0.674 

12-35 

0.048 

0.611 

0.675 

12.37 

0.036 

0.465 

0.516 

12.18 

4288.310 

0.048 

0.610 

0-674 

12-35 

0.046 

0.584 

0.648 

11.87 

0.034 

0.440 

0.491 

ii-S9 

4290.377 

0.047 

0.598 

0.662 

12.13 

0.045 

0-573 

0-637 

11.67 

0-035 

0.452 

0-503 

u.88 

4290.542 

0.045 

0.572 

0.636 

11.65 

0.047 

0-597 

0.66  1 

12.  II 

0.034 

0-439 

0.490 

ii-57 

4291.630 

0.047 

0-597 

0.661 

12.  II 

0.047 

0-597 

0.661 

12.11 

0.034 

0-439 

0.490 

ii-57 

4294.936 

0.048 

0.609 

0.673 

12-33 

0.048 

0.609 

0.673 

12.33 

0.036 

0.464 

0.515 

12.  16 

*-rfS 

0  =  79°.S 

<t>  =  79tS 

'4196.699 

0.032 

0.428 

0.479 

11.31 

0.019 

0.277 

0.311 

12.12 

0.019 

0.281 

0-315 

12.27 

4I97-257 

0.031 

0.416 

0.467 

11.03 

0.019 

0.278 

0.312 

12.15 

0.019 

0.278 

0.312 

12.15 

4203.730 

0.034 

0-454 

0.505 

11.92 

0.020 

0.282 

0.316 

12.31 

O.O2O 

0.293 

0.327 

12.74 

4209.144 

0.034 

0-453 

0.504 

11.90 

O.Oig 

0.279 

0-313 

12.19 

O.OI9 

0.281 

0-315 

12.27 

4216.136 

0.032 

0.425 

0.476 

11.24 

O.OI9 

0.280 

0-314 

12.23 

0.020 

0.281 

0.315 

12.27 

4220.509 

0.034 

0-452 

0.503 

u.88 

O.O2O 

0.293 

0.327 

12.74 

0.02O 

0.282 

0.316 

12.31 

4232-887 

0.033 

0.436 

0-487 

11.50 

0.020 

0.282 

0.316 

12.31 

O.OI9 

0.276 

0.310 

I  2.  08 

4257-8I5 

0.036 

0.470 

0.521 

12.30 

O.O2I 

0-293 

0.327 

12-74 

O.O2I 

0.294 

0.328 

12.78 

4258.477 

0.034 

0-443 

0-494 

11.66 

O.O2I 

0-293 

0.327 

12.74 

0.020 

0.286 

0.320 

12.47 

4265.418 

0.034 

0-443 

0.494 

11.66 

O.O20 

0.279 

0-313 

12.19 

O.O2O 

0.276 

0.310 

I  2.  08 

4266.081 

0.036 

0.470 

0.521 

12.30 

0.020 

0.284 

0.318 

12.39 

O.O2O 

0.284 

0.318 

12.39 

4268.915 

0.034 

0.442 

0-493 

11.64 

O.O2O 

0.280 

0.314 

12.23 

O.O2O 

0.282 

0.316 

12.31 

4276.836 

0.034 

0.441 

0.492 

11.62 

O.O2O 

0.282 

0.316 

12.31 

0.020 

0.278 

0.312 

12.15 

4284.838 

0.033 

0.427 

0.478 

11.29 

0.019 

0.272 

0.306 

11.92 

O.O2O 

0.278 

0.312 

12.15 

4287.566 

0.034 

0.440 

0.491 

"•59 

O.O2O 

0.277 

0.311 

12.12 

O.O2O 

0.285 

0.319 

12.43 

4288.310 

0.035 

0-453 

0.504 

11.90 

O.OI9 

0.272 

0.306 

11.92 

0.020 

0.279 

0-313 

12.19 

4290.377 

0.035 

0.452 

0.503 

u.88 

O.OI9 

0.272 

0.306 

11.92 

0.019 

0.272 

0.306 

11.92 

4290.542 

0.036 

0.464 

0.515 

12.  l6 

0.020 

0.280 

0.314 

12.23 

O.Oig 

0.266 

0.300 

11.69 

4291.630 

0.035 

0-453 

0-504 

11.90 

O.O2O 

0.282 

0.316 

12.31 

0.02O 

0.274 

0.308 

I2.OO 

4294.936 

0.036 

0.464 

0-515 

12.  l6 

O.O2O 

0.282 

0.316 

12.31 

0.020 

0.277 

0.311 

12.12 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1906-1907. 


47 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OP  1906-1907  —  Continued. 
Plate  a  83.     1907,  May  10,  ioh  15""  G.  M.  T.    Measured  by  A.  on  G.    Distance  from  Limb  i.i  mm.    Quality,  good. 


0         49.! 

0-n  -25.3 

P         22.4 

D        -3.0 

Diameter  168.2  mm 

Factor        1.013 


io-4  io.8  79-2  IO-7 
15.4  15.6  74.4  11.6 
26.4  26.5  63.5  6.9 


seer; 
1.044 

1. 02 1 

1.007 


<t>  =  63!$ 

<t>  =  fists 

<t>  =  74?4 

. 

A 

r 

f  +  fj 

1 

A 

V 

S  +  JIj 

J 

A 

V 

v  +  vl 

£ 

km 

km 

0 

km 

km 

O 

km 

km 

• 

4196.699 

0.048 

0.624 

0.697 

11.09 

0.049 

0.636 

0.709 

11.28 

0.030 

0-393 

0-443 

11.70 

4197-257 

0.050 

0.651 

0-724 

11.52 

0.048 

0.623 

0.696 

11.07 

0-030 

0.388 

0.438 

11.56 

4203.730          0.049 

0.630 

0.703 

11.19 

0.051 

0.658 

0-731 

11.63 

0.029 

0.382 

0-432 

11.40 

4209.144             0.049 

0.628 

0.701 

11.15 

0.052 

0.665 

0.738 

11-74 

0-030 

0-386 

0.436 

11.51 

4216.136           0.050 

0-637 

0.710 

11.30 

0.048 

0.622 

0.695 

1  1.  06 

0.030 

0.390 

0.440 

11.62 

4220.509          0.049 

0.631 

0.704 

II.  21 

0.052 

0.667 

0.740 

11.77 

0.029 

0.380 

0.430 

n-35 

4232.887           0.048 

0.618 

0.691 

10.99 

0-051 

0.656 

0.729 

1  1.  60 

0.030 

0-393 

0-443 

11.69 

4257.815 

0.050 

0.636 

0.709 

11.28 

0-053 

0.669 

0.742 

11.81 

0.030 

0.384 

0-434 

11.46 

4258.477 

0.050 

0.634 

0.707 

11.25 

0-052 

0-655 

0.728 

11.58 

0.030 

0-379 

0.429 

11.32 

4265.418 

0.050 

0.629 

0.702 

11.17 

0.050 

0-634 

0.707 

11.25 

0.031 

0.390 

0.440 

11.62 

4266.081 

0.050 

0.627 

0.700 

11.14 

0.050 

0.627 

0.700 

11.14 

0.032 

0.409 

0-459 

12.12 

4268.915 

0.051 

0.641 

0.714 

11.36 

0-051 

0.646 

0.719 

11.44 

0.029 

0.370 

0.420 

11.09 

4276.836 

0.049 

0.612 

0.685 

10.90 

0.054 

0.677 

0.750 

11-93 

0.029 

0-371 

0.421 

II.  12 

4284.838 

0.049 

0.610 

0.683 

10.87 

0.051 

0-635 

0.708 

11.26 

0.030 

0.380 

0.430 

"•35 

4287.566 

0.049 

0.617 

0.690 

10.98 

0.050 

0.629 

0.702 

11.17 

0.031 

0-394 

0-444 

11.72 

4288.310 

0.050 

0.629 

0.702 

11.17 

0.051 

0.639 

0.712 

"•33 

0.031 

0-394 

0.444 

11.72 

4290.377 

0.050 

0.623 

0.696 

II.O7 

0.052 

0.650 

0.723 

11.50 

0.028 

0-354 

0-434 

11.46 

4290.542 

0.050 

0.623 

0.696 

11.07 

0.052 

0.648 

0.721 

11.47 

0.031 

0-387 

0-437 

"•54 

4291.630 

0.050 

0.623 

0.696 

11.07 

0-052 

0-653 

0.726 

"•55 

0.030         0.384 

0-434 

11.46 

4294.936 

0.049 

0.613 

0.686 

10.92 

0.052 

0.647 

0.720 

11.46 

0.030 

0-383 

0-433 

"•43 

</>  =  74!4 

<t>  =  7?!* 

<f>  =  79*2 

4196.699 

0.031 

0.404 

0-454 

11.99 

0.019 

0.252 

0-293 

II.  IO 

0.019 

0-255 

0.296 

II.  21 

4197-257 

0.032 

0.424 

0.474 

12.51 

0.019 

0.257 

0.298 

11.29 

0.018 

0.247 

0.288 

10.91 

4203.730 

0.032 

0.418 

0.468 

12.36 

0.020 

0.268 

0.309 

11.71 

0.020 

0-273 

0.314 

11.90 

4209.144 

0.032 

0.418 

0.468 

12.36 

O.O2O 

0.267 

0.308 

11.67 

O.O2O 

0.270 

0.311 

11.78 

4216.136 

0.031 

0.401 

0.451 

11.91 

O.O2O 

0.272 

0.313 

11.86 

O.OI9 

0.248 

0.289 

10.95 

4220.509 

0.033 

0.429 

0.479 

12.65 

O.O2O 

0.260 

0.301 

11.40 

0.020 

0.271 

0.312 

11.82 

4232.887 

0.032 

0.409 

0-459 

12.12 

0.020 

0.270 

0.311 

11.78 

0.020 

0.261 

0.302 

II-44 

4257-815 

0.034 

0-435 

0.485 

12.  80 

O.O2O 

0.261 

0-302 

11.44 

O.O2O 

0.256 

0.297 

11.25 

4258.477 

0.034 

0.430 

0.480 

12.67 

O.OI9 

0.251 

0.292 

1  1.  06 

O.Oig 

0.246 

0.287 

10.87 

4265.418 

0.034 

0.432 

0.482 

12.72 

0.020 

0.267 

0.308 

11.67 

0.020 

0.256 

0.297 

11.25 

4266.081 

0.032 

0.432 

0.482 

12.72 

O.O2I 

0-274 

0.3IS 

n-93 

O.O2O 

0.261 

0-302 

11.44 

4268.915 

0.032 

0.411 

0.461 

12.17 

O.O2O 

0.266 

0.307 

11.63 

O.OI9 

0.246 

0.287 

10.87 

4276.836 

0.032 

0.404 

0-454 

11.98 

0.020 

0.262 

0.303 

11.48 

0.020 

0.264 

0-305 

11.56 

4284.838 

0.033 

0.413 

0.463 

12.22 

O.O2O 

0.259 

0.300 

n-37 

O.O2O 

0.256 

0.297 

11.25 

4287.566 

0.032 

0.405 

0-455 

12.  OI 

O.O2I 

0.269 

0.310 

"•75 

O.O2O 

0-254 

0-295 

II.  18 

4288.310 

0.031 

0.389 

0-439 

11-59 

0.020 

0.261 

0.302 

"•44 

0.020 

0.261 

0-302 

11.44 

4290.377 

0032 

0-395 

0-445 

11-75 

O.OlS 

0.233 

0.274 

10.38 

O.O2O 

0.258 

0.299 

"•33 

4290.542 

0-033 

0.412 

0.462 

12.  2O 

O.OI9 

0.248 

0.289 

10.95 

O.O2O 

0.258 

0.299 

"•33 

4291.630 

0.034 

0.432 

0.482 

12.72 

O.O2I 

0.269 

0.310 

ii-75 

0.020 

0.258 

0.299 

"•33 

4294.936 

0.032 

0-399 

0-449 

11.85 

0.020 

0-253 

0.294 

11.14 

O.O2I 

0.273 

0.314 

11.90 

| 

48     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  85.     1907,  May  30,  I2h  sm  G.  M.  T.     Measured  by  A.  on  T.     Distance  from  Limb  i.o  mm.     Quality,  good. 


P-P 


secy 


o 

68.4 

10. 

,2 

IO.2 

79-8 

4.2 

1.003 

O-fl 

-6.0 

15 

2 

15-2 

74-8 

2.8 

I.OOI 

p 

16.3 

26 

,2 

26.2 

63.8 

1.7 

I.OOO 

D 

-0.7 

Diameter 

167.9  mm 

Factor 

1.  01  2 

4-  •=  63°$ 

<t>  =  63!8 

0  =  74!8 

A 

t) 

r  +  », 

J 

A 

•e 

»  +  »! 

{ 

A 

» 

»  +  »! 

£ 

km 

km 

0 

km 

km 

. 

km 

km 

0 

4196.699 

0.054 

0.692 

0.760 

12.22 

0-055 

0.704 

0.772 

12.41 

0.032 

0.410 

0.461 

12.48 

4197-257 

0.054 

0.692 

0.760 

12.22 

0-055 

0.704 

0.772 

12.41 

0.032 

0.410 

0.461 

12.48 

4203.730 

o-oSS 

0.703 

0.771 

12.40 

0.058 

0.741 

0.809 

13.01 

0.034 

0-434 

0-485 

13-13 

4209.144 

0.058 

0.740 

0.808 

12.99 

0.056 

0.714 

0.782 

12-57 

0.034 

0-433 

0.484 

13.11 

4216.136 

0.056 

0.712 

0.780 

12-54 

0-055 

0.699 

0.767 

12.33 

0.034 

0.432 

0.483 

13.08 

4220.509 

0.056 

0.711 

0-779 

12.52 

0.058 

Q-737 

0.805 

12.95 

0.034 

0.432 

0.483 

13.08 

4232.887 

0.058 

0-734 

0.802 

I2.9O 

0.058 

o-734 

0.802 

12.90 

0.033 

0.419 

0.470 

12-73 

4257-815 

0.058 

0.727 

0-795 

12.78 

0.058 

0.727 

0-795 

12.78 

0-033 

0.413 

0.464 

12.56 

4258.477 

0.056 

0.702 

0.770 

12.38 

0-057 

0-713 

0.781 

12.56 

0.034 

0.426 

0-477 

12.92 

4265.418 

0.058 

0-725 

0-793 

12.75 

0.060 

0.749 

0.817 

13-14 

0-035 

0.438 

0.489 

13-24 

4266.081 

0.058 

0.724 

0.792 

12.74 

0.058 

0.724 

0.792 

12.73 

0.036 

0.450 

0.501 

13-57 

4268.915 

0-057 

0.710 

0.778 

12.51 

0.059 

0.736 

0.804 

12.93 

0.033 

0.412 

0.463 

12.54 

4276.836 

0.059 

0-734 

0.802 

12.90 

0.060 

0.736 

0.804 

12.93 

0-033 

0.410 

0.461 

12.48 

4284.838 

0.059 

0.732 

0.800 

12.86 

0.060 

0-744 

0.812 

13.06 

0-035 

0-434 

0.485 

13-13 

4287.566 

0.057 

0.706 

0-774 

12.45 

0.059 

0-731 

0.799 

12.85 

0-035 

0-433 

0.484 

13.10 

4288.310 

0.057 

0.706 

0-774 

12.45 

0.060 

0-743 

0.811 

13-04 

0.032 

0.396 

0.447 

12.  IO 

4290.377 

0.056 

0.693 

0.761 

12.24 

0.058 

0.718 

0.786 

12.64 

0-034 

0.421 

0.472 

12.78 

4290.542 

0-057 

0.705 

0-773 

12.43 

0.058 

0.718 

0.786 

12.64 

0.033 

0.408 

0-459 

12-43 

4291.630 

0.058 

0.717 

0-785 

12.62 

0.058 

0.704 

0.772 

12.41 

0.034 

0.420 

0.471 

12.75 

4294.936 

0-058 

0.717 

0-785 

12.62 

0.058 

0.717 

0.785 

12.62 

0.034 

0.420 

0.471 

12-75 

0  =  74?8 

0  =  79!8 

0  =  79:8 

4196.699 

0.032 

0.410 

0.461 

12.48 

0.019 

0.247 

0.287 

11.51 

0.018 

0.236 

0.276 

1  1.  06 

4197-257 

0.029 

0.372 

0.423 

"•45 

0.019 

0.242 

0.282 

11.31 

0.018 

0.231 

0.271 

10.86 

4203.730 

0.031 

0-397 

0.448 

12.13 

O.O2O 

0.257 

0.297 

11.91 

0.019 

0-247 

0.287 

11.51 

4209.144 

0.031 

0.396 

0.447 

12.10 

O.O2O 

0.256 

0.296 

11.87 

0.020 

0.256 

0.296 

11.87 

4216.136 

0.030 

0-382 

0-433 

11.72 

0.019 

0-238 

0.278 

11.15 

O.OlS 

0.234 

0.274 

10.98 

4220.509 

0.034 

0.432 

0.483 

13.08 

O.O2O 

0-255 

0.295 

11.83 

O.O2I 

0.265 

0-305 

12.23 

4232-887 

0.032 

0.405 

0.456 

12-34 

O.O2O 

0.249 

0.289 

"•59 

O.O2I 

0.264 

0.304 

12.19 

4257-815 

0.034 

0.426 

0.487 

I3-I9 

0.021 

0.259 

0.299 

11.99 

O.O2O 

0.251 

0.291 

11.67 

4258.477 

0.031 

0.389 

0.440 

11.91 

0.020 

0-254 

0.294 

11.79 

0.021 

0.266 

0.306 

12.27 

4265.418 

0.032 

0.400 

0.451 

12.21 

O.O2O 

0.246 

0.286 

11.47 

O.Oig 

0-243 

0.283 

"•35 

4266.081 

0.034 

0.424 

0-475 

12.87 

O.O2O 

0.271 

0.311 

12-47 

O.O2O 

0.246 

0.286 

"-47 

4268.915 

0.032 

0-399 

0.450 

12.19 

0.021 

0.265 

0-305 

12.23 

O.O2O 

0-255 

0.295 

11.83 

4276.836 

0-035 

0-435 

0.486 

13.16 

O.O2O 

0.254 

0.294 

11.79 

0.019 

0.240 

0.280 

11.23 

4284.838 

0.032 

0-397 

0.448 

12.13 

O.O2O 

0.249 

0.289 

"•59 

O.O2O 

0.244 

0.284 

"•39 

4287.566 

0.034 

0.421 

0.472 

12.78 

O.O2O 

0.248 

0.288 

"-5S 

O.O2O 

0.244 

0.284 

"•39 

4288.310 

0.036 

0-445 

0.496 

13-43 

0.020 

0.248 

0.288 

"•55 

0.020 

0.246 

0.286 

11.47 

4290.377 

0-035 

0-433 

0.484 

13.10 

O.O2O 

0.243 

0.283 

"•35 

O.O2O 

0.248 

0.288 

"•55 

4290.542 

0.036 

0-445 

0-495 

I3-40 

O.O2O 

0-253 

0-293 

"•75 

O.O2O 

0.251 

0.291 

11.67 

4291.630 

0-035 

0-433 

0.484 

13.10 

O.Oig 

0.241 

0.281 

11.27 

0.020 

0.248 

0.288 

"•55 

4294.936 

0.034 

0.420 

0.471 

12-75 

0.020 

0.243 

0.283 

"•35 

0.021 

0.262 

0.302 

12.  II 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


49 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  — Continued. 

Plate  w  85  —  Continued.     1907,  May  30,  12"  5™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  i.o  mm.     Quality,  good. 

p— P          ir  <t>  n  secy 

2.°8 


O          68.4 

O-O      -6.0 

P          16.3 


15.2 
26.2 


15-2 
26.2 


74.8 
63.8 


I.OOI 

I.OOO 


D     -0.7 
Diameter  167.9  mm 
Factor        1.012 


\ 

0  =  63?8 

<t>  =  63°8 

0  -  74!8 

0  =  74?8 

A 

» 

v  +  vl 

£ 

A 

V 

«"  +  »! 

£ 

A 

» 

V  +  »! 

? 

A 

D 

f  +  fj 

1 

km 

km 

0 

km 

km 

• 

km 

km 

0 

km 

km 

• 

4196.699 

0.049 

0.627 

0.695 

ii.  18 

0.048 

0.613 

0.68  1 

10.95 

0.030 

0.385 

0.436 

11.81 

0.029 

0-371 

0.422 

"•43 

4197-257 

0.049 

0.640 

0.708 

11.38 

0.048 

0.613 

0.681 

10.95 

0.031 

0-397 

0.448 

12.13 

0.029 

0.371 

0.422 

n-43 

4203.730 

0.050 

0.637 

0.704 

"•34 

0.052 

0.664 

0.732 

11.77 

0.032 

0.406 

0-457 

12.37 

0.030 

0.384 

0-435 

11.78 

4209.144 

0.052 

0.662 

0.730 

11.74 

0.052 

0.661 

0.729 

11.72 

0.032 

0-405 

0.456 

12.35 

0.031 

0-395 

0.446 

12.08 

4216.136 

0.051 

0.647 

0.715 

11.50 

0.050 

0.634 

0.702 

11.27 

0.030 

0.382 

0-433 

11.72 

0.030 

0.382 

0-433 

11.72 

4220.509 

0-053 

0.672 

0-740 

11.90 

0.052 

0.659 

0.727 

11.69 

0.033 

0.417 

0.468 

12.67 

0.032 

0.405 

0.456 

12-35 

4232-887 

0-053 

0.669 

0-737 

11.85 

0-053 

0.661 

0-737 

11.85 

0-033 

0.417 

0.468 

12.67 

0.032 

0.405 

0.456 

12-35 

4257-815 

0-055 

0.685 

0-753 

12.  II 

0-055 

0.689 

0-757 

12.17 

0.036 

0.449 

0.500 

13-54 

0.034 

0-425 

0.476 

12.89 

4258.477 

0.053 

0-659 

0.727 

11.69 

0-053 

0.661 

0.729 

11.72 

0.034 

0.423 

0-474 

12.83 

0.033 

0.387 

0.438 

11.86 

4265.418 

0.054 

0.670 

0.738 

11.87 

0.051 

0.636 

0.704 

11-32 

0.032 

0-399 

0.450 

12.18 

0-033 

0-387 

0.438 

11.86 

4266.081 

0-055 

0.683 

0-751 

I  2.  08 

0.054 

0.672 

0.740 

11.90 

0-035 

0-435 

0.486 

13.16 

0.036 

0.448 

0-499 

i3-5i 

4268.915 

0-054 

0.670 

0.738 

11.87 

0.054 

0.670 

0.738 

11.87 

0.032 

0.398 

0.449 

12.  l6 

0.034 

0.423 

0-474 

12.83 

4276.836 

0.054 

0.670 

0.738 

11.87 

0.051 

0-633 

0.701 

11.27 

0.033 

0.410 

0.461 

12.48 

0.031 

0.386 

0-437 

11.83 

4284.838 

0-053 

0.656 

0.724 

11.64 

0-053 

0-655 

0.723 

11.63 

0-033 

0.409 

0.460 

12.45 

0.034 

0.421 

0-472 

12.78 

4287.566 

0-053 

0.655 

0.723 

11.63 

0-054 

0.667 

0-735 

11.82 

0.032 

0.396 

0.447 

12.  IO 

0-033 

0.409 

0.460 

12.46 

4288.310 

0-053 

0.655 

0.723 

11.63 

0-053 

0-655 

0-723 

11.63 

0-033 

0.408 

0-459 

12-43 

0.034 

0.421 

0.472 

12.78 

4290.377 

0.056 

0.692 

0.760 

12.22 

0.052 

0-643 

0.711 

"•43 

0.034 

0.420 

0.471 

12.75 

0.032 

0.396 

0-447 

12.  IO 

4290.542 

0-055 

0.680 

0.748 

12.03 

0.054 

0.667 

0-735 

11.82 

0-033 

0.408 

0-459 

12.43 

0.034 

0.420 

0.471 

12-75 

4291.630 

0.054 

0.667 

0-735 

11.82 

0.054 

0.667 

0-735 

11.82 

0.036 

0.444 

0-495 

13.40 

0.034 

0.420 

0.471 

12.75 

4294.936 

0.052 

0.642 

0.710 

11.42 

0-053 

0.654 

0.722 

ii.  61 

0.034 

0.420 

0.471 

12-75 

0.033 

0.408 

0-459 

12.43 

Plate  w  91.     1907,  June  23,  5''  55""  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  1.2  mm.    Quality,  good. 

p  —  P          it  <f>  i) 


Q 

Q-ii 
P 
D 


91.1 

16.7 

6.4 

2.1 


37-0 
52-7 
68.2 
83.2 


37-o 
52-7 
68.2 
83-2 


53-o 

37-3 

21.8 

6.8 


3-4 
2.6 

2.2 
2.1 


I.OO2 
I.OOI 
I.OOI 
I.OOI 


Diameter  168.1  mm 
Factor        1.014 


<t>  = 

6?8 

0  = 

2I?8 

0  = 

31°3 

0  = 

S3?o 

A 

V 

D  +  Tj 

( 

A 

V 

r  +  r, 

£ 

A 

tl 

»  +  »! 

£ 

A 

V 

»  +  »! 

£ 

km 

km 

0 

km 

km 

o 

km 

km 

0 

km 

km 

0 

4196.699 

0.148 

1.901 

2-035 

14-55 

0.130 

.669 

.798 

13-76 

0.102 

1.312 

1.429 

12.75 

0.076 

0.978 

1.071 

12.63 

4197-257 

0.148 

I.OOO 

2.034 

14-55 

0.130 

.669 

•798 

13-76 

O.IO2 

1.311 

1.428 

12.74 

0.076 

0-977 

1.070 

12.62 

4203.730 

0.150 

1.919 

2.053 

14.68 

0.132 

.691 

.820 

13-93 

O.IO4 

I-33J 

1.448 

12.92 

0.077 

0.987 

1.080 

12.74 

4209.144 

0.150 

1.917 

2.051 

14.67 

0.132 

.688 

.817 

13-91 

O.IO4 

1.328 

r-445 

12.89 

0.078 

i.ooo 

1.093 

12.89 

4216.136 

0.149 

1.900 

2.034 

14-55 

0.130 

•658 

.787 

13-67 

O.IO4 

1-325 

1.442 

12.87 

0.078 

0-997 

.090 

12.86 

4220.509 

0.150 

1.906 

2.040 

14-59 

0.132 

.678 

.807 

13-83 

O.IO4 

1-325 

1.442 

12.87 

0.078 

0-995 

.088 

12.83 

4232.887 

0.150 

I.OOI 

2-035 

H-55 

0.132 

•673 

.802 

'3-79 

0.105 

1-332 

1.449 

12.93 

0.078 

0.990 

•083 

12.78 

4257-815 

0.152 

1.909 

2.043 

14.61 

0-135 

.691 

.820 

13-93 

0.107 

1-344 

1.461 

13-04 

0.080 

1.005 

.098 

12.95 

4258.477 

0.152 

1.907 

2.041 

14.60 

0-133 

.667 

.796 

13-74 

0.106 

1-330 

1.447 

12.91 

0.078 

0.980 

•073 

12.66 

4265.418 

0.152 

1.905 

2-039 

14.58 

0-133 

-665 

•  794 

13-73 

O.IO7 

1-340 

1-457 

13.00 

0.079 

0.991 

.084 

12.79 

4266.081 

0.153 

1.914 

2.048 

14.65 

0.134 

.677 

.806 

13.82 

O.IOS 

1-352 

1.469 

13.11 

0.080 

1.002 

•095 

12.92 

4268.915 

0.152 

1.892 

2.026 

14.49 

0-134 

.671 

.800 

13-77 

O.IO7 

I-324 

1.441 

12.86 

0.080 

I.OOO 

•093 

12.89 

4276.836 

0.152 

1.891 

2.025 

14.48 

0-134 

1.668 

•797 

'3-75 

O.IO/ 

1.322 

1-439 

12.84 

0.081 

I.OIO 

-103 

12.89 

4284.838 

0.152 

1.889 

2.023 

14.46 

0.134 

1.666 

•795 

13-74 

0.107 

I-33I 

1.448 

12.92 

0.080 

0-997 

.090 

12.86 

4287.566 

0-153 

1.902 

2.036 

I4-56 

O.I3S 

1.677 

.806 

13.82 

O.IO9 

1-354 

1.471 

13-13 

0.079 

0-985 

.078 

12.72 

4288.310 

0.153 

1.899 

2.033 

14-54 

0.135 

1.676 

•805 

13.81 

O.IO? 

1.328 

1-445 

12.89 

0.081 

1.007 

.100 

12.98 

4290.377 

0.152 

1.885 

2.019 

14.44 

0.134 

I-675 

.804 

13.80 

o.  106 

1.310 

1.427 

"•73 

0.080 

0-995 

.088 

12.83 

4290.542 

0-153 

1-895 

2.029 

I4-5I 

0.136 

1.686 

-815 

13.89 

0.107 

1.329 

1.446 

12.90 

0.080 

0-993 

.086 

12.81 

4291.630 

0.152 

1.883 

2.017 

14.42 

0.135 

I-673 

1.802 

13-79 

0.108 

1.340 

1-457 

13.00 

0.082 

1.018 

.III 

13-" 

4294.936 

0.153 

1.894 

2.028 

14.50 

0.136 

1.684 

1.813 

13-87 

.  0.108 

1-338 

1-455 

12.98 

0.082 

I.OIO 

•103 

13.01 

50    AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  86.     1907,  May  31,  4h  $$m  G.  M.  T.     Measured  by  A.  on  G.     Distance  from  Limb  1.3  mm.     Quality,  Good. 


t>-P 


seci 


o 

69.1 

8.9 

8.9 

81.1 

4-4 

1.003 

0-0 

-5-3 

13- 

9 

9 

76.1 

2.8 

I.OOI 

p 

16.0 

25- 

9 

25' 

9 

64.1 

1.6 

I.OOO 

D 

-0.6 

45' 

,2 

45- 

a 

44.8 

0.9 

I.OOO 

Diameter 

168.5  mm 

60 

,3 

60, 

jj 

29.8 

0.8 

I.OOO 

Factor 

1.016 

75' 

2 

75- 

2 

14.8 

o-7 

I.OOO 

0  = 

Mia 

0  = 

20 

0  = 

44t8 

X 

A 

li 

.  +  ., 

« 

A 

V 

,-,, 

• 

A 

V 

.  +  ., 

« 

4196.699 

0.143 

km 

.837 

km 
1.971 

14.47 

0.116 

km 
1-493 

km 
1.617 

13-23 

0.095 

km 
1.225 

km 
I-33I 

O 

I3-3I 

4197.257 

0.142 

.826 

1.960 

14-39 

O.I  20 

1-544 

1.668 

13-65 

0.092 

1.183 

1.289 

12.89 

4203.730 

0.142 

.827 

1.961 

14.40 

0.119 

I-525 

1.649 

13-48 

0.094 

1.208 

I-3I4 

I3-I4 

4209.144 

0.146 

.874 

2.008 

14-74 

0.124 

1.582 

1.706 

13.96 

0.098 

1.249 

•355 

13-55 

4216.136 

0.142 

.809 

1-943 

14.27 

0.116 

1.481 

1.605 

13-13 

0.096 

1.226 

•332 

I3-32 

4220.509 

0.146 

.861 

1-995 

14.64 

O.I2I 

1.546 

1.670 

13.66 

O.IOO 

1.269 

•375 

13-75 

4232.887 

0.147 

1.863 

1.997 

14.66 

0.123 

1.564 

1.688 

13.81 

0.091 

1.160 

.266 

12.66 

4257.815 

0.143 

1-793 

1.927 

14-15 

O.I2I 

I.527 

1.651 

13-50 

0.096 

1.207 

•313 

13-13 

4258.477 

0.149 

1-873 

2.007 

14.74 

0.125 

1.569 

1.693 

13-85 

O.IOO 

1.262 

.368 

13.68 

4265.418 

0.148 

1-855 

1.989 

14.61 

O.I2I 

'•SIS 

1.639 

13-40 

0.094 

1.176 

.282 

12.82 

4266.081 

0.142 

1-779 

1-913 

14.05 

0.127 

1-590 

1.714 

14.03 

0.092 

I-I54 

.260 

12.60 

4268.915 

0.146 

1.824 

1.958 

14-38 

0.123 

1.538 

1.662 

13.60 

0.092 

1.162 

.268 

12.68 

4276.836 

0.147 

1-833 

1.967 

14-45 

0.127 

1.584 

1.708 

13.98 

0.095 

1.188 

•294 

12.94 

4284.838 

0.147 

1.828 

1.962 

14.41 

0.128 

1-594 

1.718 

14.06 

0.095 

1.187 

•293 

12.93 

4287  566 

0.144 

I  7o6 

I  O3O 

14.17 

O.I23 

I     ^31 

I    '  '  "  's 

I2.C4. 

<f  «u  I  .  j«v 

4288.310 

0.142 

/  y 

1.766 

yo 
1.904 

13.96 

-  *    J 
O.I24 

1-537 

1.661 

*O"O*T 

13.59 

0.094 

1.169 

•275 

12.75 

4290.377 

0.147 

1.824 

1.958 

14.38 

0.125 

1.551 

1-675 

13.70 

0.096 

1.192 

.298 

12.98 

4290.542 

0.149 

1.849 

1.983 

14-56 

0.123 

i-53i 

1-655 

13.54 

0.096 

1.197 

•303 

13-03 

4291.630 

0.150 

1.867 

2.001 

14.69 

0.125 

1-557 

i.  68  1 

13.75 

0.094 

I-I75 

.281 

12.81 

4294.936 

0.149 

1.850 

1.984 

J4-57 

0.123 

1-529 

I.6S3 

13-52 

0.095 

1.180 

.286 

12.86 

0  = 

64°! 

0  = 

76:1 

0  = 

8* 

4196.699 

0.052 

0.664 

0.738 

I2.OO 

0.025 

0.322 

0.370 

10.93 

0.018 

0.232 

0.269 

12.34 

4197.257 

0.053 

0.682 

0.756 

12.27 

0.024 

0.309 

0-357 

10.55 

0.019 

0.242 

0.279 

12.80 

4203.730 

0.057 

0.729 

0.803 

I3-05 

O.O28 

0-355 

0.403 

11.91 

0.018 

0.231 

0.268 

12.30 

4209.144 

0.055 

0.701 

0-775 

1  2.  60 

0.028 

0-354 

0.402 

11.88 

0.019 

0.244 

0.281 

12.89 

4216.136 

0.054 

0.685 

0-759 

12.32 

0.025 

0.322 

0.370 

10.93 

0.017 

0.218 

0.255 

11.70 

4220.509 

0.055 

0.702 

0.776 

I2.6l 

0.029 

0.368 

0.416 

12.29 

0.019 

0.245 

0.282 

12.94 

4232.887 

0.056 

0.711 

0.785 

12.76 

O.O28 

0-356 

0.404 

11.94 

0.018 

0.224 

0.261 

11.98 

4257.815 

0.058 

0.698 

0.772 

12-55 

0.030 

0.378 

0.426 

12.59 

0.019 

0.241 

0.278 

12.76 

4258.477 

0.056 

0.703 

o-777 

12.63 

0.031 

0.388 

0.436 

12.88 

0.019 

0.236 

0.273 

12.53 

4265.418 

0.056 

0.699 

0-773 

12-57 

0.031 

0.392 

0.440 

13.00 

0.018 

0.228 

0.265 

12.  l6 

4266.081 

0.057 

0.718 

0.792 

12.87 

0.030 

o.377 

0.425 

12.56 

0.019 

0.238 

0.275 

12.62 

4268.915 

0.054 

0.671 

0-745 

12.  IO 

O.O28 

0-356 

0.404 

11.94 

0.018 

0.223 

0.260 

"•93 

4276.836 

0.057 

0-715 

0.789 

12.84 

0.031 

0.390 

0.438 

12.94 

0.018 

O.220 

0.257 

11.79 

4284.838 

0-055 

0.680 

0-754 

12.24 

O.O28 

0-345 

0-393 

11.61 

0.017 

0.212 

0.249 

"•43 

4287.566 

0.057 

0.712 

0.786 

12.78 

0.031 

0.388 

0.436 

12.88 

0.018 

O.224 

0.261 

11.98 

4288.310 

0.056 

0.698 

0.772 

12-55 

0.028 

0-349 

0-397 

"•73 

0.019 

0.234 

0.271 

12.44 

4290.377 

0-053 

0.656 

0.730 

11.87 

0.030 

0.363 

0.411 

12.14 

o.o  1  8 

0.226 

0.263 

12.07 

4290.542 

0.056 

0.691 

0.765 

12.42 

0.028 

0-373 

0.421 

12.44 

0.019 

0.234 

0.271 

12.44 

4291.630 

0.059 

0.730 

0.804 

I3-07 

0.030 

0.368 

0.416 

12.29 

0.019 

0.238 

0.275 

12.62 

4294.936 

0.055 

0.680 

0-754 

12.24 

0.028 

0.348 

0.396 

11.70 

0.018 

0.223 

0.260 

"•93 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


Plate 


TABLE  4.  —  RESULTS  TOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
87.     1907,  June  22,  nh  iom  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  0.6  mm.    Quality,  good. 


p-f 


secy 


Q 

o-a 
p 

D 


90.4 

16.0 

6.8 

2.0 


Diameter  167.0  mm 
Factor        i  .007 


30-9 

3°-9 

59-i 

3-9 

I.OO2 

37-9 

37-9 

52.1 

3-2 

1.002 

51-4 

Si-4 

38-6 

2.6 

1.  001 

66.9 

66.9 

23.1 

2.2 

I.OOI 

81.9 

81.9 

8.1 

2.O 

1.00  1 

0  = 

8!  i 

0  = 

23!l 

<t>  = 

38!6 

/ 

A 

D 

»  +  »i 

£ 

A 

V 

»+», 

e 

A 

t> 

»  +  », 

i 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.148 

1.887 

2.O2I 

14.49 

0.129 

1.646 

•774 

13.69 

0.099 

-265 

1-379 

"•S3 

4197-257 

0.147 

1.875 

2.OO9 

14.41 

0.130 

1.658 

.786 

13-77 

O.IOO 

•277 

I-39I 

12.64 

4203.730 

0.149 

1.896 

2.030 

14.56 

0.132 

1.679 

.807 

13-95 

0.103 

•3" 

I-425 

12.94 

4209.144 

0.150 

1.901 

2.035 

14-59 

0-133 

1.689 

.817 

14.02 

0.103 

•305 

1.419 

12.89 

4216.136 

0.148 

1-875 

2.OO9 

14.41 

0.130 

1.647 

•775 

13-70 

O.IOI 

.280 

1-394 

12.66 

4220.509 

0.150 

1.897 

2.031 

14-56 

0.134 

1.694 

1.822 

14.06 

0.104 

•314 

1.428 

12.97 

4232.887 

0.150 

1.889 

2.023 

14-51 

0.133 

I-675 

1.803 

13-92 

0.103 

.297 

1.411 

12.82 

4257.815 

0.153 

1.905 

2.039 

14.62 

0.136 

1.696 

1.824 

14.08 

0.106 

.320 

1-434 

13-03 

4258.477 

0.152 

1.890 

2.O24 

14-51 

0.134 

1.667 

1-795 

13-85 

0.104 

.297 

1.411 

12.82 

4265.418 

0.152 

1.890 

2.024 

14-51 

0-134 

1.666 

1-794 

13-85 

0.106 

.312 

1.426 

12-95 

4266.081 

0-154 

I-9I5 

2.049 

14.69 

0-135 

1.677 

1.805 

13-93 

0.107 

•324 

1.438 

13.06 

4268.915 

0-IS3 

1.895 

2.029 

14-55 

0.134 

1.664 

1.792 

13-83 

0.107 

•323 

1-437 

13-05 

4276.836 

0.152 

1.882 

2.OI6 

14.46 

0.136 

1.679 

1.807 

13-95 

0.106 

•3" 

I-42S 

12.94 

4284.838 

O.IS3 

1.889 

2.023 

14-51 

0.136 

1.678 

i.  806 

13-94 

0.105 

.296 

1.410 

12.81 

4287.566 

0.152 

1.876 

2.010 

14.41 

0.136 

1.677 

1.805 

13-93 

o.  106 

.308 

1.422 

12.92 

4288.310 

0.152 

1.875 

2.009 

14.41 

0-135 

1.665 

1-793 

13.84 

0.105 

.294 

1.408 

12.79 

4290.377 

0.151 

1.861 

1-995 

14-31 

0.132 

1.627 

1-755 

13-55 

0.103 

.270 

1.384 

12.57 

4290.542 

0.152 

1-873 

2.007 

14.40 

0.132 

1.626 

J-754 

13-54 

0.104 

.281 

1-395 

12.67 

4291.630 

0.152 

1.872 

2.006 

14-39 

0.134 

1.648 

1.776 

13-71 

0.104 

1.280 

1-394 

12.66 

4294.936 

0.153 

1.882 

2.016 

14.46 

0-133 

1.636 

1.764 

13.62 

0.104 

1.280 

1-394 

12.66 

<t>  = 

S2tl 

<t>  = 

52!' 

0  = 

Srfi 

4196.699 

0.072 

0.922 

1.024 

11.83 

0.074 

0.946 

1.040 

12.02 

0.059 

0-755 

0.837 

"•57 

4197-257 

0.074 

0.918 

I.OI2 

11.70 

0.073 

0-933 

1.027 

II.8? 

0.060 

0.767 

0.849 

11.74 

4203.730 

0.076 

0.969 

1.063 

12.29 

0.076 

0.969 

1.063 

12.29 

0.063 

0.803 

0.885 

12.23 

4209.144 

0.075 

0-954 

1.048 

12.  II 

0.076 

0.967 

1.061 

12.26 

0.062 

0-789 

0.871 

12.04 

4216.136 

0.073 

0.926 

I.O2O 

11-79 

0.074 

0-939 

1-033 

11.94 

0.060 

0.762 

0.844 

11.67 

4220.509 

0.076 

0.963 

1-057 

12.22 

0.076 

0.963 

1-057 

12.22 

0.062 

0.786 

0.868 

11.99 

4232.887 

0.077 

0.971 

1.065 

12.31 

0.078 

0.983 

1.077 

12-45 

0.063 

0.789 

0.871 

12.23 

4257-815 

0.080 

0.999 

1.093 

12.63 

0.080 

0.999 

1-093 

12.63 

0.064 

0.800 

0.882 

12.19 

4258.477 

0.078 

0.970 

1.064 

12.30 

0.078 

0-973 

1.067 

12-33 

0.063 

0.787 

0.869 

12.01 

4265.418 

0.078 

0.969 

1.063 

12.29 

0.078 

0.972 

1.066 

12.32 

0.063 

0.785 

0.867 

11-99 

4266.081 

0.080 

0.996 

1.090 

I  2.  60 

0.078 

0.971 

1.065 

12.31 

0.065 

0.807 

0.889 

12.29 

4268.915 

0.079 

0-979 

1-073 

12.40 

0.077 

0.956 

1.050 

12.14 

0.064 

0.794 

0.876 

12.  II 

4276.836 

0.078 

0.967 

1.061 

12.26 

0.077 

0-955 

1.049 

12.13 

0.065 

0.806 

0.888 

12.28 

4284.838 

0.079 

0.976 

1.070 

12.37 

0.078 

0.964 

1.058 

12.23 

0.065 

0.804 

0.886 

12.25 

4287.566 

0.078 

0.966 

i.  060 

12.25 

0.078 

0.964 

1.058 

12.23 

0.064 

0.802 

0.884 

12.22 

4288.310 

0.078 

0.965 

1-059 

12.24 

0.077 

0-954 

1.048 

12.  II 

0.064 

0.791 

0.873 

12.07 

4200.377 

0.079 

0.974 

i.  068 

12-34 

0.077 

0-952 

1.046 

I2.O9 

0.063 

0.778 

0.860 

11.89 

4290.542 

0.078 

0.963 

1-057 

12.22 

0.077 

0.952 

1.046 

12.09 

0.063 

0.778 

0.860 

11.89 

4291.630 

0.079 

0-973 

1.067 

12-33 

0.077 

0.952 

1.046 

I2.O9 

0.064 

0.789 

0.871 

12.04 

4294.936 

0.079 

0-973 

1.067 

12-33 

0.078 

0.961 

i-OSS 

12.19 

0.063 

0.777 

0.859 

11.88 

52     AN   INVESTIGATION   OF   THE   ROTATION   PERIOD    OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  w  88.     1907,  June  22,  nh  40™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  0.6  mm.     Quality,  good. 


P-P 


secy 


O 

Q-a 
p 

D 


90.4 

16.0 

6.8 

2.0 


Diameter  167.0  mm 
Factor        1.007 


30-9 

30.9 

S9-i 

3-9 

I.OO2 

37-9 

37-9 

52-1 

3-2 

1.002 

Si-4 

Si-4 

38.6 

2.6 

I.OOI 

66.9 

66.9 

23-1 

2.2 

I.OOI 

81.9 

81.9 

8.1 

2.0 

I.OOI 

\ 

4>  = 

8°  i 

<t>  = 

23!  i 

0  = 

3»!6 

A 

A 

V 

»  +  », 

1 

A 

v 

n  +  tij 

« 

A 

t 

»  +  », 

i 

km 

km 

O 

km 

km 

0 

km 

km 

0 

4196.699 

0.147 

1.878 

2.OI2 

14-43 

0.128 

I-633 

1.761 

13-59 

O.IOO 

1.277 

•391 

12.64 

4197-25? 

0.148 

.888 

2.O22 

14-50 

0.128 

I-633 

1.761 

13-59 

0.099 

.264 

-378 

12.52 

4203.730 

0.150 

.909 

2.043 

14.65 

0-133 

1.689 

1.817 

14.02 

0.103 

•3" 

•425 

12.94 

4209.144 

0.151 

.917 

2.051 

14.71 

0.131 

1.664 

1.792 

13.83 

O.IO2 

•295 

.409 

I  2.  80 

4216.136 

0.149 

.888 

2.O22 

14.50 

0.129 

I-635 

I-763 

13.61 

O.IOI 

.281 

•395 

12.67 

4220.509 

0.152 

.922 

2.056 

14.74 

0.132 

1.669 

1-797 

13.87 

0.103 

•303 

•417 

12.87 

4232.887 

0.152 

.914 

2.048 

14.69 

0.132 

1.662 

1.790 

13.82 

0.104 

1.309 

•423 

1293 

4257-815 

0-154 

1.920 

2.054 

14-73 

0-134 

1.668 

1.796 

13.86 

0.105 

1.309 

•423 

12.93 

4258-477 

0-153 

1.901 

2-035 

14-59 

0.132 

1.643 

.771 

13-67 

0.103 

1.281 

•395 

12.67 

4265.418 

0-153 

1.899 

2-033 

14.58 

0.132 

1.642 

.770 

13-66 

0.103 

1.279 

•393 

12.65 

4266.081 

0.154 

1.909 

2-043 

14-65 

0-135 

1.677 

-805 

13-93 

0.105 

1.306 

.440 

13.08 

4268.915 

0.154 

1.908 

2.O42 

14.64 

0-135 

1.676 

.804 

13.92 

0.103 

1.276 

•390 

12.63 

4276.836 

0-153 

1.894 

2.028 

14-54 

0.132 

1.634 

.762 

13.60 

0.103 

1.276 

•390 

12.63 

4284.838 

0-153 

1.885 

2.019 

14.48 

0.134 

1-654 

.782 

13-75 

O.IO4 

1.284 

•398 

I2.7O 

4287.566 

0-153 

1.885 

2.019 

14.48 

0-133 

1.639 

.767 

13-64 

0.104 

1-283 

•397 

12.69 

4288.310 

0.154 

1.896 

2.030 

14-56 

0.133 

1.639 

.767 

13.64 

O.IO4 

1.283 

•397 

12.69 

4290.377 

0.152 

1.871 

2.005 

14.38 

0-133 

1.638 

.766 

13-63 

O.IO4 

1.282 

•396 

12.68 

4290.542 

0.152 

1.882 

2.016 

14.46 

0-134 

1.650 

.778 

13.72 

0.104 

1.281 

•395 

12.67 

4291.630 

0-154 

1.894 

2.O28 

14-54 

0.134 

1.649 

•777 

13-72 

0.104 

1.281 

•395 

12.67 

4294.936 

0-153 

1.882 

2.0l6 

14.46 

0-133 

1.636 

.764 

13.62 

O.IO4 

1.280 

•394 

12.66 

<t>  = 

s* 

0  = 

S2ti 

0  = 

S9?i 

4196.699 

0.074 

0-949 

1.043 

12.05 

0.073 

0-937 

1.031 

11.92 

0.059 

0.758 

0.840 

11.61 

4197-257 

0.075 

0.958 

1.052 

12.  l6 

0.074 

0.946 

1.040 

12.02 

0.060 

0.768 

0.850 

n-75 

4203.730 

0.076 

0.969 

1.063 

12.28 

0.076 

0.969 

1.063 

12.29 

O.O62 

0.790 

0.872 

12.06 

4209.144 

0.077 

0.979 

1.073 

12.40 

0.076 

0.964 

1-058 

12.23 

O.O62 

0.788 

0.870 

12.03 

4216.136 

0.075 

0.952 

1.046 

12.09 

0.074 

0-939 

i-°33 

11.94 

O.o6o 

0.761 

0.843 

11.65 

4220.509 

0.077 

0-975 

1.069 

12.36 

0.077 

0-975 

1.069 

12.36 

0.063 

0.797 

0.869 

I2.OI 

4232.887 

0.078 

0-983 

1.077 

12.45 

0.078 

0.983 

1.077 

12-45 

O.O62 

0.781 

0.863 

n-93 

4257-815 

0.080 

0-997 

1.091 

12.  6l 

0.080 

0.996 

1.090 

I  2.  60 

O.O66 

0.824 

0.906 

12-43 

4258.477 

0.079 

0.983 

1.077 

12-45 

0.078 

0.971 

1.065 

12-31 

O.O62 

0.772 

0.854 

11.81 

4265.418 

0.079 

0.982 

1.076 

12-44 

0.079 

0.982 

1.076 

12.44 

0.063 

0.783 

0.865 

12.95 

4266.081 

0.080 

0.994 

i.  088 

12.57 

0.080 

0-994 

i.  088 

12-57 

0.064 

0-795 

0.874 

12.12 

4268.915 

0.079 

0.981 

1-075 

12.42 

0.079 

0.980 

1.076 

12.44 

0.064 

0-794 

0.876 

12.  II 

4276.836 

0.080 

0.992 

i.  086 

12.55 

0.080 

0.992 

i.  086 

I2.55 

0.064 

0-793 

0.875 

12.  IO 

4284.838 

0.078 

0.968 

1.062 

12.27 

0.079 

0.979 

1-073 

12.40 

0.064 

0.792 

0.874 

I  2.08 

4287.566 

0.080 

0.988 

1.082 

12.51 

0.079 

0.978 

1.072 

12.39 

0.064 

0.791 

0.873 

I2.O7 

4288.310 

0.078 

0.966 

i.  060 

12.25 

0.080 

0.988 

1.082 

12.51 

0.063 

0-779 

0.861 

11.90 

4200.377 

0.078 

0.965 

1.059 

12.24 

0.079 

0.976 

1.070 

12.37 

0.063 

0.777 

0.859 

11.88 

4290.542 

0.079 

0-975 

1.069 

12.36 

0.080 

0.987 

1.081 

12.49 

0.064 

0.789 

0.871 

12.04 

4291.630 

0.080 

0.986 

1.080 

12.48 

0.080 

0.986 

1.080 

12.48 

0.064 

0.788 

0.870 

12.03 

4294.936 

0.081 

0.997 

1.091 

12.61 

0.082 

I.OIO 

1.104 

12.76 

0.063 

0.776 

0.858 

11.86 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1906-1907. 


S3 


Plate  w  ! 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
1907,  June  22,  I2h  15™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  0.6  mm.     Quality,  good. 


p-P 


sec*) 


0 

90.4 

3°-5 

30.5 

59-5 

3-9 

1.003 

o-n 

16.0 

37-5 

37-5 

52.5 

3-2 

1.002 

p 

6.8 

51.0 

51.0 

39-° 

2.6 

I.OOI 

D 

2.O 

66.5 

66.5 

23-5 

2.2 

I.OOI 

Diameter 

167.0  mm. 

81.5 

8i.s 

8-5 

2.0 

I.OOI 

Factor 

1.007 

0  = 

8!s 

0  = 

23!$ 

0  = 

39!° 

X 

A 

V 

v  +  vl 

£ 

A 

V 

»  +  »! 

£ 

A 

V 

»  +  »! 

£ 

km 

km 

o 

km 

km 

0 

km 

km 

o 

4196.699 

0.146 

-855 

1.989 

14.28 

0.129 

1.645 

1-773 

13-73 

0.098 

1.261 

1-374 

12-55 

4I97-2S7 

0.146 

-855 

1.989 

14.28 

0.128 

I-633 

1.761 

13-63 

0.099 

1.269 

1-382 

12.62 

4203.730 

0.148 

.875 

2.009 

14.42 

0.132 

1.  680 

1.  808 

13-99 

O.IOI 

1.285 

1.398 

12.79 

4209.144 

0.147 

.863 

1.997 

14-34 

0.132 

1.676 

1.804 

13.96 

O.IO2 

1-295 

1.408 

12.86 

4216.136 

0.146 

.850 

1.984 

14-23 

0.130 

1.647 

•775 

13-75 

O.IOI 

1.281 

1-394 

12.73 

4220.509 

0.149 

-877 

2.  on 

14.44 

0.133 

1.682 

.810 

14.01 

0.104 

1.316 

1.429 

13-05 

4232.887 

0.148 

.864 

1.998 

14-35 

0.132 

1.662 

•790 

13.86 

O.IO2 

.285 

1.398 

12.77 

4257-8IS 

0.150 

.871 

2.005 

14-39 

0.136 

1.693 

.821 

14.10 

0.105 

•3" 

1.424 

13.01 

4258.477 

0.149 

.856 

1.990 

14.28 

0.134 

1.667 

•795 

13.90 

0.104 

.298 

1.401 

12.80 

4265.418 

0.150 

-857 

1.991 

14.29 

0.133 

1.654 

.782 

13.80 

0.106 

•317 

1.430 

13.06 

4266.081 

0.151 

.870 

2.004 

14.38 

0-137 

1-703 

.831 

14.17 

0.105 

•305 

1.418 

12.95 

4268.915 

0.148 

.838 

1.972 

14.16 

0.135 

1.672 

.800 

13-93 

0.104 

.292 

1.405 

12.84 

4276.836 

0.150 

•855 

1989 

14.28 

0.134 

1.659 

•787 

13.84 

0.106 

•309 

1.422 

12.99 

4284.838 

0.150 

•853 

1.987 

14.27 

0.134 

1-653 

.78! 

13-79 

0.104 

.283 

1.396 

12.75 

4287.566 

0.149 

.840 

J-974 

14.18 

0-133 

1.639 

-767 

13.68 

0.106 

.308 

1.421 

12.98 

4288.310 

0.148 

.825 

1-959 

14.06 

0-133 

1.639 

.767 

13.68 

0.104 

.281 

1-394 

12.73 

4290.377 

0.146 

1.800 

1-934 

13-88 

0-132 

1.626 

•754 

13-58 

0.103 

•293 

1.406 

12.84 

4290.542 

0.150 

I-845 

1-979 

14.21 

0.136 

1.673 

.801 

13-94 

0.106 

•304 

1.417 

12.94 

4291.630 

0.150 

1.845 

1-979 

14.21 

0.134 

1.649 

•777 

13.76 

0.104 

.280 

1-393 

12.73 

4294.936 

0.147 

I-84S 

1.979 

14.21 

0.133 

1.636 

•764 

13-66 

0.104 

.280 

1-393 

12.73 

<t>  = 

5z!s 

0  = 

5z!s 

0  = 

59!S 

4196.699 
4I97-2S7 

0.074 
0.074 

0.950 
0.950 

1.044 
1.044 

12.  18 
12.18 

0.076 
0.076 

0.970 
0.970 

1.064 
1.064 

12.41 
12.41 

0.059 
0.060 

0.758 
0.766 

0.838 
0.846 

11.72 
11.83 

4203.730 

0.076 

0.970 

1.064 

12.41 

0.077 

0.980 

1.074 

12.53 

0.062 

0.792 

0.872 

12.  2O 

4209.144 

0.077 

0.980 

1.074 

12.53 

0.078 

0.991 

1.085 

12.66 

0.062 

0.789 

0.869 

12.  l6 

4216.136 

0.075 

0.960 

1.054 

12.29 

0.076 

0.967 

i.  06  1 

12.37 

0.061 

0.778 

0.858 

12.00 

4220.509 

0.077 

0.976 

1.070 

12.48 

0.079 

0.999 

1.093 

12-75 

0.062 

0.786 

0.866 

12.  II 

4232.887 

0.078 

0.984 

1.078 

12.57 

0.078 

0.983 

1.077 

12.56 

0.062 

0.778 

0.858 

I2.OO 

4257.815 

0.080 

1.  000 

1.094 

12.76 

0.080 

0.998 

1.092 

12.74 

0.065 

0.812 

0.892 

12.48 

4258.477 

0.079 

0.986 

1.080 

12.60 

0.079 

0.984 

1.078 

12.57 

0.064 

0.794 

0.874 

12.22 

4265.418 

0.079 

0.985 

1.079 

12.58 

0.081 

1.009 

1.103 

12.86 

0.065 

0.805 

0.885 

12.38 

4266.081 

0.081 

1.  006 

I.IOO 

12.83 

0.082 

1.  020 

1.114 

12.99 

0.064 

0-793 

0.873 

12.21 

4268.915 

0.080 

0-993 

1.087 

12.68 

0.097 

0.980 

1.074 

12-53 

0.064 

0.792 

0.872 

12.  2O 

4276.836 

0.080 

0-993 

1.087 

12.68 

0.080 

0.991 

1.085 

12.66 

0.064 

0.792 

0.872 

12.  2O 

4284.838 

0.081 

1.003 

1.097 

12.79 

0.080 

0.988 

1.082 

12.62 

0.065 

0.803 

0.883 

12-35 

4287.566 

0.080 

0.990 

1.084 

12.64 

0.080 

0.988 

1.082 

12.62 

0.064 

0.791 

0.871 

12.  l8 

4288.310 

0.081 

I.OOO 

1.094 

12.76 

0.081 

1.  002 

1.096 

12.78 

0.064 

0.791 

0.871 

12.  l8 

4290.377 

0.080 

0.988 

1.082 

12.62 

0.081 

I.OOO 

1.094 

12.76 

0.063 

0.778 

0.858 

I2.0O 

4290.542 

0.080 

0.987 

1.081 

12.  6l 

0.081 

I.OOI 

1.094 

12.76 

0.062 

0.767 

0.847 

11.85 

4291.630 

0.082 

I.  Oil 

1.105 

12.89 

0.08  1 

0.998 

1.092 

12.74 

0.063 

0-777 

0.857 

11-99 

4294.936 

0.081 

0.997 

1.091 

12.72 

0.083 

1.  02  1 

1.115 

13.00 

0.063 

0.777 

0.857 

11.99 

54     AN   INVESTIGATION    OF   THE   ROTATION   PERIOD   OF   THE    SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  4.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1906-1907  —  Continued. 
Plate  <•>  90.     1907,  June  23,  sh  zom  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.2  mm.     Quality,  good. 


P-P 


scci) 


o 

o-n 
p 

D 


91.1 

16.7 

6.4 

2.1 


Diameter  168.1  mm 
Factor        1.014 


25-5 

25.6 

64.4 

4.6 

I.OO4 

34-5 

34-5 

55-5 

3-7 

I.OO2 

37-o 

S2.7 
68.2 

37-o 

S2-7 
68.2 

53-° 
37-3 

21.8 

3-4 

2.6 
2.2 

I.OO2 
I.OOI 
I.OOI 

83-2 

83-2 

6.8 

2.1 

I.OOI 

0  = 

6!8 

<t>  = 

2I°8 

0  = 

3?!3 

X 

A 

T 

»  +  ?! 

t 

A 

V 

v  +  vl 

i 

A 

V 

V  +  tlj 

{ 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.149 

I-9I3 

2.047 

14.64 

0.128 

1.646 

1-775 

13.58 

0.102 

1.312 

1.429 

12.75 

4I97-2S7 

0.149 

I-9I3 

2.047 

14.64 

0.129 

I-657 

1.786 

13.67 

O.IO2 

1.311 

1.428 

12.74 

4203.730 

0.150 

1.921 

2-055 

14.70 

0.130 

1.666 

1-795 

13-74 

0.103 

1.321 

•438 

12.83 

4209.144 

0.151 

1.925 

2.059 

14.72 

0.130 

1.662 

1.791 

13.70 

O.IO4 

1-330 

•447 

12.91 

4216.136 

0.150 

I-9I3 

2.047 

14.64 

0.129 

1.646 

J-775 

13-58 

O.IO3 

I-3I5 

•432 

12.78 

4220.509 

0.150 

1.909 

2.043 

I4.6l 

0.130 

1-655 

1.784 

13-65 

O.IO4 

1.324 

.441 

12.86 

4232.887 

0.151 

I-9I3 

2.047 

14.64 

0.130 

1.648 

1-777 

13.60 

0.105 

1-332 

•449 

12.93 

42S7-8IS 

0-153 

1.920 

2.054 

14.69 

0.131 

1.651 

1.780 

13.62 

O.IO4 

1.307 

1.424 

12.70 

4258.477 

0.152 

1.905 

2.039 

14.58 

0.131 

1.648 

1-777 

13.60 

O.I  06 

1-330 

1.447 

12.91 

4265.418 

0.152 

1.002 

2.036 

I4-56 

0.132 

1.656 

1-785 

13.66 

0.105 

I.3I8 

1-435 

12.80 

4266.081 

0-153 

I-9I3 

2.047 

14.64 

0.132 

1.654 

1-783 

13-64 

0.106 

1.328 

1-445 

12.89 

4268.915 

0.152 

1.899 

2-033 

14-54 

0.132 

1.650 

1-779 

13.61 

0.106 

1.326 

1-443 

12.88 

4276.836 

0.152 

1.897 

2.031 

I4-52 

0.132 

1.646 

1-775 

13.58 

0.106 

1.322 

1-439 

12.84 

4284.838 

0.152 

1.894 

2.028 

14.50 

0.132 

1.644 

1-773 

13-57 

0.106 

1.320 

1-437 

12.82 

4287.566 

0-153 

1.902 

2.036 

14.56 

0-133 

1.654 

1-783 

13.64 

0.106 

1.320 

1-437 

12.82 

4288.310 

0-153 

1.899 

2.033 

14-54 

0.134 

1.664 

1-793 

13.72 

0.106 

1.318 

1-435 

12.80 

4290.377 

0.152 

1.886 

2.020 

14-45 

0-133 

1.650 

1.779 

13.61 

0.106 

1.318 

1-425 

12.71 

4290.542 

O.IS3 

1.896 

2.030 

14.52 

0.132 

1.652 

1.781 

13.63 

0.107 

I-327 

1.444 

12.88 

4291.630 

0.152 

1.883 

2.017 

1442 

0-133 

1.647 

1.776 

13.59 

0.105 

1.302 

1.419 

12.66 

4294.936 

0.153 

1.894 

2.028 

14.50 

0-133 

1.647 

1.776 

13.59 

0.107 

I-324 

1.441 

12.86 

0  = 

S3!o 

0  = 

ss!s 

0  = 

64!4 

4196.699 

0.074 

0-953 

.046 

12-34 

0.071 

0.912 

i.  002 

12.56 

0.050 

0.644 

0.715 

"•75 

4I97-257 

0.075 

0.964 

•057 

12.47 

0.072 

0.925 

1.015 

12.72 

0.050 

0.644 

0-715 

"•75 

4203.730 

0.077 

0.987 

.080 

12-74 

0.072 

0.924 

1.014 

12.71 

0.051 

0.657 

0.728 

11.96 

4209.144 

0.076 

0-973 

.066 

12.58 

0.072 

0.921 

I.  Oil 

12.67 

0.051 

0.655 

0.726 

"•93 

4216.136 

0.077 

0.983 

.076 

12.69 

0.072 

0.919 

1.009 

12.65 

0.050 

0.641 

0.712 

11.70 

4220.509 

0.077 

0.981 

.074 

12.67 

0.073 

0.930 

I.O2O 

12.78 

0.051 

0.651 

0.722 

11.86 

4232.887 

0.077 

0.977 

.070 

12.62 

0.073 

0.926 

1.016 

12.73 

0.052 

0.661 

0.732 

12.03 

4257-8I5 

0.079 

0-993 

.086 

12.81 

0.075 

0.941 

1.031 

12.92 

0.054 

0.680 

0.751 

12.34 

4258.477 

0.078 

0.980 

•073 

12.66 

0.074 

0.928 

1.018 

12.76 

0.052 

0-653 

0.724 

11.90 

4265.418 

0.078 

0-979 

.072 

12.65 

0.074 

0.926 

1.016 

12.73 

0-053 

0.665 

0.736 

12.09 

4266.081 

0.078 

0-977 

.070 

12.62 

0.074 

0.926 

I  .Old 

12.73 

0.054 

0-677 

0.748 

12.29 

4268.915 

0.078 

0-975 

.068 

12.60 

0.073 

0.912 

I.OO2 

12.56 

0.054 

0.675 

0.746 

12.26 

4276.836 

0.078 

0-973 

.066 

12.58 

0.074 

0-923 

I.OI3 

12.70 

0.054 

0.674 

0-745 

12.24 

4284.838 

0.079 

0.984 

.       -077 

12.68 

0.076 

0.946 

1.036 

12.99 

0.054 

0.675 

0.746 

12.26 

4287.566 

0.079 

0-983 

.076 

12.69 

0.074 

0.922 

I.OI2 

12.68 

0.054 

0.673 

0.744 

12.22 

4288.310 

0.080 

o-995 

.088 

12.83 

0.075 

0.932 

I.O22 

12.81 

0.053 

0.661 

0.732 

12.03 

4290.377 

0.079 

0.981 

•074 

12.67 

0.073 

0.908 

0.998 

12.51 

0.053 

0.660 

0-731 

12.01 

4290.542 

0.080 

0-993 

.086 

12.81 

0.076 

0-943 

1-033 

12-95 

0.054 

0.671 

0.742 

I2.I9 

4291.630 

0.079 

0.979 

.072 

12.65 

0.074 

0.918 

1.  008 

12.63 

0-053 

0.658 

0.729 

11.98 

4294.936 

0.080 

0.991 

.084 

12.79 

0.074 

0.917 

I.OO7 

12.62 

0.052 

0.646 

0.717 

".78 

The  results  for  Plate  w  91  are  given  on  page  49. 


MEAN   RESULTS   FOR   EACH   PLATE   FROM   ALL   LINES.      OBSERVATIONS   OF    1906-1907.          55 


In  order  to  arrange  the  results  of  Table  4  in  a  convenient  form  for  effective  discussion  I  have  col- 
lected the  values  in  three  ways  :  (i)  mean  results  for  each  plate  from  all  lines  ;  (2)  mean  results  for  each 
latitude  from  all  lines ;  (3)  mean  results  for  each  line  from  all  plates.  These  summaries  are  found  in 
Tables  5,  6,  and  7.  The  values  of  v  +  vl  and  £  in  Table  5  are  the  means  for  the  separate  values  given 
in  Table  4.  Table  6  is  a  rearrangement  of  Table  5  and  indicates  the  combination  of  points  of  latitude 
used  in  the  derivation  of  normal  positions.  Table  7  is  found  directly  from  the  values  of  the  individual 
lines  and  forms  the  basis  for  a  discussion  of  the  behavior  of  the  various  lines  employed. 

TABLE  5.  —  MEAN  RESULTS  FOR  EACH  PLATE  FROM  ALL  LINES.    OBSERVATIONS  OF  1906-1907. 


PLATE 
No. 

DATE. 

No.  OF 

LINES. 

0 

r  +  flj 

1 

PLATE 
No. 

DATE. 

No.  OF 
LINES. 

</> 

»  +  », 

J 

1906 

0 

km 

• 

lgo6 

0 

km 

0 

<"    3 

May  3 

20 

9.8 

2.012 

14.49 

10  26 

June  1  6 

20 

0.0 

2.073 

14.72 

24.7 

I.80S 

14.11 

15.0 

1-977 

14-52 

39-7 

I.4I9 

13.10 

30.0 

1-637 

13-41 

54-6 

1.004 

12.31 

45-0 

1.276 

1  2.80 

69-5 

0.598 

12.12 

60.0 

0.861 

12.  19 

83-6 

0.192 

12.23 

74-9 

0.444 

13.12 

w    6 

May  6 

19 

10.7 

2-035 

14.70 

co  27 

June  16 

20 

o.o 

2.065 

14.66 

25-7 

1-793 

14-13 

15.0 

1-954 

14.36 

40.6 

1.396 

I3.°5 

30.0 

1-657 

13-59 

55-6 

0.990 

12.44 

45-o 

1.270 

12.75 

70.4 

0.589 

12.47 

60.0 

0.827 

11.74 

84.6 

0.177 

13-35 

74-9 

0-435 

11.85 

<o    8 

May  19 

19 

0.9 

2.064 

14.65 

co  30 

Oct.  19 

20 

O.I 

2-075 

14-73 

iS-4 

1.921 

I4-52 

15.0 

1.936 

14.22 

30.4 

1.702 

14.01 

30.0 

1.646 

13-49 

45-4 

1.322 

I3-36 

44-8 

1.326 

13.26 

75-3 

0.448 

12-53 

59-7 

0.844 

11.88 

74-2 

0.416 

10.87 

10  19 

June  12 

20 

o. 

2-053 

I4-58 

10  31 

Oct.  19 

20 

O.I 

2.080 

14.76 

IS- 

1.944 

14.29 

15.0 

1.961 

14.41 

30- 

I-675 

13-74 

30.0 

1.678 

13-76 

45- 

1.280 

12.87 

44-8 

1.274 

12-74 

60. 

0.873 

12.44 

59-7 

0.867 

12.20 

75- 

0.460 

12.70 

74-2 

0.450 

11.74 

w  20 

June  12 

20 

O.I 

2.065 

14.66 

W35 

Nov.  ii 

20 

-0-5 

2.078 

14-75 

IS-' 

1.930 

14.19 

74.2 

0.482 

12.56 

30.1 

1.661 

13.62 

45-1 

1.268 

12.75 

(036 

Nov.  ii 

20 

-0.5 

2.067 

14.68 

60.  i 

0.867 

12.34 

14-5 

1.980 

14.51 

75-i 

0.423 

11.68 

29.4 

1.670 

13.60 

01  21 

June  12 

2O 

O.I 

IS-I 

2.059 
'•937 

14.62 
14.24 

44-6 
59-3 

1-253 
0.850 

12.49 
11.82 

16.1 

1.938 

14-31 

74-2 

0.451 

11.76 

30.1 

1.665 

13-66 

""37 

Nov.  n 

2O 

-0.7 

2.073 

14.72 

45-1 

1.274 

12.81 

14-3 

i-957 

14.34 

60.  i 

0.859 

12.24 

29-3 

1.687 

13-75 

7S-i 

0.428 

11.41 

44-2 

1.266 

12-54 

a  23 

June  15 

2O 

o.o 

2.054 

14.58 

59-2 

0.877 

12.  l6 

15.0 

1-934 

14.22 

74-o 

0.461 

11.88 

30.0 
4S-o 
59-o 
75-° 

1.669 
1.260 
0.857 
0.436 

13-68 
12.65 
11.82 
"•95 

1038 

Nov.  ii 

2O 

-0.7 
14-3 
29-3 

44.2 

2.082 
1-959 
1-677 
1.284 

14.78 
13-35 
13-65 
12.72 

<o  24 

June  15 

20 

0.0 

2-065 

14.66 

59-2 

0.896 

12.42 

15.0 

1-937 

14.24 

74.0 

0.485 

12.49 

30.0 

45  -o 
60.0 

1.674 
1.272 
0.872 

13-72 
12-77 
12.38 

"39 

Nov.  ii 

2O 

-0.7 
14-3 

2.086 
1.964 

14.81 

14.38 

75-o 

0.419 

12.04 

29-3 

1.686 

13-72 

co  25 

June  15 

20 

o.o 

15.0 
30.0 

2.060 
1.960 
1-663 

14.62 
14.41 
13-63 

44.2 
59-2 
74-o 

1.292 
0.896 
0.488 

12.79 

12.43 
12.56 

4S-° 

1.272 

12.77 

<"39i 

Dec.  18 

20 

O.I 

2.IOI 

14.92 

60.0 

0.861 

12.22 

iS-i 

1-975 

14-53 

7S-o 

0-437 

H.98 

30.1 

1.704 

13-99 

56      AN  INVESTIGATION  OF  THE  ROTATION  PERIOD   OF  THE   SUN   BY   SPECTROSCOPIC  METHODS. 
TABLE  5.  —  MEAN  RESULTS  FOR  EACH  PLATE  FROM  ALL  LINES.    OBSERVATIONS  OF  1906-1907  —  Continued. 


PLATE 
No. 

DATE. 

No.  OF 
LINES. 

0 

•  4-  »i 

s 

PLATE 
No. 

DATE. 

No.  OF 

LINES. 

</> 

•  +  »i 

1 

1906 

O 

km 

0 

i  go? 

O 

km 

° 

u  40 

Dec.  1  8 

20 

0. 

2.097 

14.89 

w  64 

Apr.  7 

20 

77-5 

0-363 

11.92 

O. 

iS- 

2.103 
1-974 

14-93 
14-51 

w  67 

Apr.  7 

20 

77-5 

0-371 

12.  16 

iS- 

1-977 

14-53 

w  78 

Apr.  7 

20 

77-5 

0.369 

12.10 

30. 

30. 

1.699 
1.704 

13-94 
13.98 

01  69 

Apr.  7 

20 

77-5 

0.369 

12.  IO 

w  41 

Dec.  18 

20 

O. 

2.086 

14.81 

w  81 

Apr.  22 

20 

67.2 

0.656 

12.02 

0. 

2.076 

14-74 

67.2 

0.649 

11.89 

IS- 

1-957 

14-38 

72.5 

0.501 

11.83 

iS- 

1.960 

14.40 

72-5 

0.497 

"•74 

3°- 

i-7°3 

13-97 

79-5 

0.315 

12.27 

30- 

1.690 

13-87 

79-5 

0.3H 

12.24 

u  46 

Dec.  1  8 

20 

44-4 

1.294 

12.86 

"83 

May  10 

20 

63-5 

0.700 

11.14 

44-4 

1.294 

12.86 

63-5 

0.720 

ii-45 

44-4 

1.298 

12.90 

74-4 

0.465 

12.28 

59-4 

0.884 

12-33 

74-4 

0.436 

11.51 

59-4 

0.892 

12.44 

79-2 

0.302 

11.44 

59-4 

0.892 

12.43 

79-2 

0.300 

iJ-37 

047 

Dec.  18 

20 

35-4 

1-537 

13-39 

085 

May  30 

20 

63.8 

0.730 

"•74 

35-4 

1.516 

13.20 

63.8 

0.722 

11.62 

44-4 

1.308 

13.00 

74-8 

0-454 

12.30 

Si-9 

1.090 

12.54 

74-8 

0.462 

12.52 

Si-9 

i.  088 

12.53 

igO? 

S9-4 

0.897 

12.50 

"85 

May  30 

20 

63-8 

0.782 

12.58 

w  50 

Feb.  3 

20 

7-5 

2-3 

38.2 
54-° 
69-5 

2.01  1 
1-835 
I-SH 
I.OI4 
0.604 

14-39 
14.18 
13.68 
12.25 
12.25 

63.8 
74.8 
74-8 
79.8 
79.8 

0.792 

0-474 
0.464 
0.291 
0.289 

12.75 
12.82 
12.56 
11.67 
11.58 

77-8 

0.3II 

10.44 

w86 

May  31 

20 

14.8 

1.966 

14.44 

77.8 

0-333 

u.  18 

19 

29.8 

1.668 

13-65 

"55 

Feb.  15 

2O 

7-5 

2.049 

14.67 

20 

44-8 

1.304 

13.04 

22.4 

1.847 

14.18 

20 

64.1 

0.770 

12.52 

38.3 

1.464 

13.22 

20 

76.1 

0.408 

12.06 

u  56 

Feb.  15 

2O 

7-5 

2.012 

14-43 

2O 

81.1 

0.268 

12.28 

22.4 

1.851 

14.20 

w  87 

June  22 

20 

8.1 

2.020 

14-49 

38.3 

1-454 

13.16 

23.1 

1-793 

13.84 

S4-o 

1.040 

12.56 

38.6 

1.411 

12.82 

69-S 

0.612 

12.41 

52-1 

1.059 

12.24 

to  60 

Feb.  28 

2O 

6-5 

2.043 

14-59 

52-1 

1-055 

12.  2O 

6-5 

2.046 

14.62 

59-i 

0.869 

12.01 

20.4 
28.1 

1.841 
1.679 

13-94 
13-52 

u88 

June  22 

20 

8.1 
23.1 

2.031 
1.780 

14.56 
13-73 

3S-o 

1.512 

13.10 

38.6 

1.401 

12.74 

43-7 

1.285 

12.62 

52.1 

1.071 

12.38 

5°-5 

1.  091 

12.19 

52-1 

1.071 

12.38 

w  61 

Feb.  28 

16 

43-7 

1.265 

12.42 

59-i 

0867 

12.  OO 

18 
18 
17 
18 

SO-S 
59-5 
S9-S 
6S-3 

1.105 
0.836 
0.836 
0.679 

12-33 
11.69 
1  1.  69 
11.53 

089 

June  22 

20 

8-5 
23-5 
39-0 

1.986 
1.787 
1.405 

14.26 
13.84 
12.84 

17 
18 
18 

65-3 
65-3 
6S-3 

0.679 
0.724 
0.722 

"•S3 
12.30 
12.27 

52-5 
52-5 
59-5 

1.079 
i.  086 
0.866 

12-59 
12.67 
12.  II 

u>  62 

Feb.  28 

20 

-6.0 

2.042 

14-57 

o>  90 

June  23 

20 

6.8 

2.039 

14.58 

7-9 

1.997 

14-32 

21.8 

1.782 

I3.63 

15-6 

1-993 

14.69 

37-3 

1-437 

12.82 

22.S 

1-789 

13-75 

55-5 

1.015 

12.71 

30.2 

I-655 

13-59 

53-o 

i-°73 

12.66 

38-1 

1.511 

13.64 

64.4 

0-732 

12.03 

"63 

Feb.  28 

20 

7.2 

2.056 

14.67 

w  91 

June  23 

20 

6.8 

2-034 

14-55 

20.6 

1.839 

13-95 

21.8 

1.804 

13.80 

28.2 

1.674 

I3-48 

37-3 

1-447 

12.91 

35-i 

1-535 

13-32 

53-o 

1.089 

12.84 

So-7 

1.058 

11.86 

43-8 

1.283 

12.63 

MEAN   RESULTS    FOR   EACH   LATITUDE   FROM   ALL   LINES.      OBSERVATIONS   OF    1906-1907.       57 


TABLE  6. —  MEAN  RESULTS  FOR  EACH  LATITUDE  FROM  ALL  LINES.    OBSERVATIONS  OF  1906-1907. 


PLATE 

PLATE 

£ 

PLATE 

PLATE 

No. 

<t> 

P  +  P! 

1 

No. 

<t> 

r  PJ 

£ 

No. 

<t> 

»  +  pt 

1 

No. 

0 

P  +  P, 

£ 

» 

km 

•> 

" 

km 

0 

O 

km 

0 

o 

km 

0 

u    8 

0.9 

2.064 

14.65 

w    3 

24.7 

1.805 

14.11 

<u    8 

45-4 

1.322 

13.36 

«    3 

69-5 

0.598 

12.12 

19 

O.I 

2-053 

14.58 

6 

25-7 

1-793 

I4.I3 

19 

45-1 

1.280 

12.87 

6 

70.4 

0.589 

12-47 

20 

O.I 

2.065 

14.66 

So 

23-3 

1.835 

I4.I8 

20 

45-i 

1.268 

12.75 

So 

69-5 

0.604 

12.25 

21 

O.I 

2.059 

14.62 

55 

22.4 

1.847 

I4.I8 

21 

1.274 

12.81 

56 

69-5 

0.612 

12.41 

23 

o.o 

2.054 

14.58 

56 

22.4 

1.851 

I4.2O 

23 

45-0 

1.260 

12.65 

61 

65-3 

0.679 

"•53 

24 

0.0 

2.065 

14.66 

60 

20.4 

1.841 

13-94 

24 

45-0 

1.272 

12.77 

61 

65-3 

0.679 

"•53 

25 

o.o 

2.060 

14.62 

62 

22.5 

1.789 

13-75 

25 

45-0 

1.272 

12.77 

61 

65-3 

0.724 

12.30 

26 

o.o 

2.073 

14.72 

63 

2O.6 

1.839 

13-95 

26 

45-0 

1.276 

I  2.  80 

61 

65-3 

0.722 

12.27 

2? 

0.0 

2.065 

14.66 

87 

23.1 

1-793 

13.84 

27 

45-0 

1.270 

12-75 

81 

67.2 

0.656 

12.  02 

3° 

O.I 

2.075 

14-73 

88 

23.1 

1.780 

13-73 

30 

44.8 

1.326 

13.26 

81 

67.2 

0.649 

11.89 

31 

O.I 

2.080 

14.76 

89 

23.5 

1.787 

13.84 

31 

44.8 

1.274 

12-74 

83 

63-5 

0.700 

11.14 

35 

0.5 

2.078 

14-75 

90 

21.8 

1.782 

I3-63 

36 

44.6 

1-253 

12.49 

83 

63-5 

0.700 

11.14 

36 

o-S 

2.067 

14.68 

91 

21.8 

1.804 

13.80 

37 

44-2 

1.266 

12.54 

83 

63-5 

0.720 

"•45 

37 
38 

0.7 

o-7 

2.073 
2.082 

14.72 
14.78 

Means    22.7         1.811         13.94 

38 
39 

44-2 
44-2 

1.284 
1.292 

12.72 
12.79 

83 
85 

63-5 
63.8 

0.720 
0.730 

"•45 
11.74 

39, 

0-7 

2.086 

14.81 

46 

44-4 

1.294 

12.86 

85 

63.8 

f\i   Q 

0.722 

_o  „ 

11.62 

n     _Q 

39* 

O.I 

2.IOI 

14.92 

46 

44-4 

1.294 

12.86 

O1) 

63.8 

0.702 

12.58 

40 

O.I 

2.097 

14.89 

«    8 

30.4 

1.702 

14.01 

46 

44-4 

1.298 

12.90 

8S 

63.8 

0.792 

12-75 

40 

O.I 

2.103 

14-93 

'9 

30.1 

J.675 

13-74 

47 

44-4 

1.308 

13.00 

86 

64.1 

0.770 

12.52 

41 

O.I 

2.086 

14.81 

20 

30.1 

1.661 

13.62 

60 

43-7 

1.285 

12.62 

00 

64.4 

0.732 

12.03 

41 

O.I 

2.076 

14-74 

21 

30.1 

1-665 

13.66 

61 

43-7 

1.265 

12.42 

Alciins   6^6        o  604.         1  1  06 

Means     0.2         2.074         I4-73 

23 

30.0 

1.669 

13-68 

63 

Ofi 

43-8 

.    .     0 

1.283 

12.63 

24 

30.0 

1.674 

13-72 

OO 

44.8 

1.304 

!3-04 

25 

30.0 

1.663 

13-63 

Means   44.6        1.283         12.80 

w    8 

75-3 

0.448 

12.53 

26 

30.0 

1*637 

I  7.41 

19 

75.1 

0.460 

12.70 

<"    3 
6 

9.8 
10.7 

2.OI2 
2-035 

14.49 
14.70 

27 
30 
31 

30.0 
30.0 
30.0 

1-657 
1.646 
1.678 

13-59 
13-49 
13-76 

6 

54-6 
55-6 

1.004 
0.990 

12.31 
12.44 

20 
21 
23 

75-i 
7S-i 
75-o 

0.423 
0.428 
0.436 

11.68 
11.81 
"•95 

50 
55 
56 
60 
60 
62 
62 
63 
8? 
88 
89 

7-5 
7-5 
7-5 
6-5 
6-5 
6.0 

7-9 
7-2 
8.1 
8.1 
8-5 

2.OII 
2.049 
2.OI2 
2.043 
2.046 
2.042 
1.997 
2.056 
2.02O 
2.031 
1.986 

14-39 
14.67 

14-43 
14-59 
14.62 

14-57 
14-32 
14.67 
14.49 
14.56 
14.26 

36 

37 
38 
39 
39* 
40 
40 

41 
60 
62 

29.4 
29-3 
29-3 
29-3 
30.1 
30.1 
30.1 
30.1 
30.1 
28.1 
30.2 

1.670 
1.687 
1.677 
1.686 
1.704 
1.699 
1.704 
1-703 
1.690 
1.679 
1-655 

13.60 
13-75 
13-65 
13-72 
13-99 
13-94 
13.98 

13-97 
13-87 
I3-52 
13-59 

47 
47 
50 
56 
60 
61 
63 
87 
87 
88 
88 

Qrt 

5i-9 
51-9 
54-0 
54-o 
50-5 
50.5 
50.7 
52.1 
52-1 
52.1 
S2.I 

1.090 
1.  088 
1.014 
1.040 
1.091 
1.105 
1.058 
1.059 

1.055 
1.071 
1.071 

I2-54 
12.53 
12.25 
12.56 
12.19 

12.33 
11.86 
12.24 

12.20 
12.38 
12.38 

24 
25 
26 

27 
30 
31 

35 
36 
37 
38 
39 

75-° 
75-0 
74-9 
74-9 
74-2 
74-2 
74.2 
74.2 
74.0 
74-0 
74.0 

0-439 
0.436 

0-445 
0-435 
0.416 
0.450 
0.482 

0-45  1 
0.461 
0.485 
0.488 

12.04 
11.98 

12.12 
11.85 
10.87 
11-74 
12.56 
11.76 

11.88 
12.49 
12.56 

90 

6.8 
6.8 

2-039 
2.034 

14.58 
14-55 

63 
86 

28.2 
29.8 

1.674 
1.668 

13-48 
13-65 

89 
89 

52-5 

52-5 

1.079 
1.086 

I2-59 
12.67 
12.66 

50 
50 

77-8 
77-8 

0.311 
0-333 

10.44 
11.18 

Means      7.7         2.028        14.53 

Means    29.8        1.676        13.71 

9° 
90 

53-O 
55-5 

I-°73 
1.015 

12.71 

64 

£  _ 

77-5 

0-363 

11.92 

T   l\      •  A 

91 

53-o 

1.089 

12.84 

67 
68 

77-5 
77-5 

0-371 
0.369 

I  2.16 
12.10 

Means   52.7        1.060         12.43 

69 

Q 

77-5 

0.369 

12.10 

8l 

72-5 

0.501 

1  1  .83 

w    8 

iS-4 

I.92I 

I4-S2 

W      2 

39-7 

1.419 

13.10 

w  19 

60.  i 

0-873 

12.44 

81 

72.5 

0-497 

11.74 

19 

iS-i 

1.944 

14.29 

3 

39-7 

1.419 

13.10 

20 

60.  i 

0.867 

12.34 

83 

74-4 

0.465 

12.28 

20 

iS-i 

1.930 

14.19 

6 

40.6 

1.396 

13-05 

21 

60.  i 

0.859 

12.24 

83 

74-4 

0.465 

12.28 

21 

1-937 

14.24 

47 

35-4 

1-537 

13-39 

23 

59-0 

0.857 

11.82 

83 

74-4 

0.436 

"•Si 

21 

i6!i 

1.938 

14-31 

47 

35-4 

14516 

13.20 

24 

60.0 

0.872 

12.38 

83 

74-4 

0.436 

11.51 

23 

15.0 

1-934 

14.22 

So 

38.2 

1.514 

13.68 

25 

60.0 

0.861 

12.22 

8S 

74-8 

0-454 

12.30 

24 

IS-O 

1-937 

14.24 

55 

38-3 

1.464 

13.22 

26 

60.0 

0.861 

12.19 

85 

74-8 

0.462 

12.52 

25 

15.0 

1.960 

14.41 

56 

38-3 

1-454 

13.16 

26 

60.0 

0.861 

12.19 

85 

74-8 

0-474 

12.82 

26 

15.0 

J-977 

14-52 

60 

35-° 

1.512 

13.10 

27 

60.0 

0.827 

11.74 

85 

74-8 

0.464 

12.56 

26 

15.0 

1-977 

14-52 

62 

38-1 

1.511 

13-64 

3° 

59-7 

0.844 

11.88 

86 

76.1 

0.408 

I  2.  06 

27 

15.0 

1-954 

14.36 

63 

35-i 

1-535 

13-32 

31 

59-7 

0.867 

12.  2O 

Means   75.1        0.435         ".98 

30 

15.0 

1.936 

14.22 

87 

38-6 

1.411 

12.82 

36 

59-3 

0.850 

11.82 

31 

15.0 

1.961 

14.41 

88 

38-6 

1.401 

12.74 

37 

59-2 

0.877 

12.  l6 

36 

I4-S 

1.980 

89 

39-o 

1.405 

12.84 

38 

59-2 

0.896 

12.42 

<"    3 

83.6 

0.192 

12.23 

37 

14-3 

1-957 

H-34 

90 

37-3 

1-437 

12.82 

39 

59-2 

0.896 

12.43 

6 

84.6 

0.177 

13-53 

38 

14-3 

1-959 

14-35 

9' 

37-3 

1-447 

12.91 

46 

59-4 

0.884 

12.33 

81 

79-5 

0-315 

12.27 

39 
39  i 

14-3 

1.964 
1-975 

14-38 
14-53 

Means   37.8        1.461         13.13 

46 
46 

59-4 
59-4 

0.892 
0.892 

12.44 
12.43 

81 
83 

79-5 
79.2 

0.314 
0.302 

12.24 
11.44 

40 

iS-i 

1-974 

14-51 

47 

59-4 

0.897 

12.50 

83 

79-2 

0.302 

11.44 

40 

1-977 

14-53 

61 

59-5 

0.836 

11.69 

83 

79-2 

0.300 

"•37 

41 

15.1 

1-957 

14.38 

61 

59-5 

0.836 

11.69 

83 

79.2 

0.300 

"•37 

41 

15.1 

1.960 

14.40 

8? 

59-i 

0.869 

12.01 

85 

79.8 

0.291 

11.67 

62 

IS-6 

1-993 

14.69 

88 

59-i 

0.867 

I2.OO 

85 

79.8 

0.289 

11.58 

86 

14.8 

1.966 

14.44 

89 

59-5 

0.866 

I  J.IT 

86 

81.1 

0.268 

12.28 

Means   15.0        1.957         M-4O 

VI  cans    59.6        0.867         12.15 

Means   80.4        0.277         ".80 

58      AN   INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC  METHODS. 
TABLE  7. —  MEAN  RESULTS  FOR  EACH  LINE  FROM  ALL  PLATES.    OBSERVATIONS  OF  1906-1907. 


*-.!. 

0  =  7t7 

0  =  15!° 

0  -  2,!7 

X 

ELEMENT. 

No.  OF 

No.  OF 

No.  OF 

No.  OF 

PLATES. 

»  +  »! 

* 

PLATES. 

»  +  »! 

1 

PLATES. 

«-  +  »! 

* 

PLATES. 

v  +  vl 

1 

km 

0 

km 

o 

km 

0 

km 

0 

4196.699 

La 

21 

2.077 

14-75 

14 

2.O22 

14.49 

24 

1.946 

14.30 

12 

1.798 

13.84 

4197-257 

CN 

21 

2.081 

14.78 

IS 

2.O26 

14-51 

24 

1-957 

14.38 

13 

1.804 

13.88 

4203.730 

Cr 

21 

2.096 

14.88 

IS 

2.045 

14.65 

23 

1-974 

14.51 

13 

1.818 

13.99 

4209-144 

Zr 

21 

2.103 

14-93 

IS 

2.O42 

14-63 

24 

1-977 

14.53 

13 

1.827 

14.07 

4216.136 

CN 

21 

2.057 

14.61 

IS 

2.028 

14-53 

24 

1-943 

14.28 

13 

1.799 

13.84 

4220.509 

Fe 

21 

2.089 

14-83 

IS 

2-039 

14.61 

24 

1.978 

14-54 

13 

1.824 

14.04 

4232-887 

Fe 

21 

2.089 

14.83 

IS 

2.038 

14.60 

24 

1-977 

14-53 

13 

1.824 

14.04 

42S7-8IS 

Mn 

21 

2.090 

14.84 

15 

2.054 

14.72 

24 

1-974 

14-51 

13 

1.832 

14.10 

4258-477 

Fe 

21 

2-074 

14-73 

IS 

2.030 

14-54 

24 

1.965 

14-45 

13 

1.810 

13-93 

4265-418 

Fe 

21 

2.075 

14-74 

IS 

2.027 

14-54 

24 

1.968 

14.46 

13 

1.801; 

13.89 

4266.081 

Mn 

21 

2.080 

H-77 

IS 

2.045 

14.65 

24 

1.962 

14.42 

13 

1.830 

14.08 

4268.915 

Fe 

21 

2.072 

14.71 

15 

2.030 

14-54 

24 

1.966 

14-45 

13 

1.814 

13.96 

4276.836 

-Zr 

21 

2.070 

14.70 

IS 

2.O2I 

14.48 

24 

1-954 

14-35 

13 

i.  806 

13.90 

4284.838 

Ni 

21 

2.067 

14.68 

15 

2.021 

14.48 

24 

1.958 

14-39 

13 

1.811 

13.94 

4287.566 

Ti 

21 

2.072 

14.71 

IS 

2.0l6 

14.44 

24 

I-956 

14.38 

13 

1.810 

13.93 

4288.310 

Ti,  Fc 

21 

2.070 

14.70 

15 

2.OI6 

14.44 

24 

1.949 

14-33 

13 

i.  806 

13.90 

4290.377 

Ti 

21 

2-053 

14.58 

15 

2-003 

H-35 

24 

1-943 

14.28 

13 

1.800       13.85 

4290.542 

Fe 

21 

2-058 

14.62 

15 

2.0l6 

14.44 

24 

1-949 

U-33 

13 

i.  806       13-90 

4291.630 

Fe 

21 

2.061 

14.63 

15 

2.010 

14.40 

24 

I-95I 

14-34 

13 

1.801        13.86 

4294-936 

Zr 

21 

2.063 

14.65 

15 

2.018 

14.46 

24 

1.946    !     14-30 

13 

1-798 

13-84 

X 

ELEMKNT. 

0=29?8 

0=37!8 

0  =  44!6 

0  =  52!? 

4196.699 

La 

24 

1.  660 

13-58 

15 

1.446 

12.97 

22 

1.266 

12.62 

16 

1.034 

12.  II 

4197-257 

CN 

24 

1.674 

13-70 

16 

1-445 

12.98 

22 

1.271 

12.67 

17 

1-037 

12.15 

4203.730 

Cr 

23 

1.693 

13.84 

16 

1.467 

13.18 

22 

1.282 

12.78 

18 

1-057 

12.38 

4209.144 

Zr 

24 

1.698 

13-89 

16 

1.469 

13.20 

23 

1.302 

12.98 

18 

1-057 

12.38 

4216.136 

CN 

24 

I-653 

13-52 

16 

I-45I 

13.04 

23 

1.266 

12.62 

18 

1.038 

12.16 

4220.509 

Fe 

24 

1.697 

13.88 

16 

1.470 

13.21 

23 

1.296 

12.92 

18 

i.  060 

12.42 

4232-88? 

Fe 

24 

1.689 

13.82 

16 

1.465 

1^.16 

23 

1.287 

12.83 

18 

1.058 

12.40 

4257-8I5 

Mn 

24 

1.694 

13.86 

16 

1.478 

13-28 

23 

1.301 

12.97 

18 

1-075 

12.59 

4258.477 

Fe 

24 

1.682 

I3-76 

16 

1.461 

I3-I3 

23 

1.289 

12.85 

18 

1.063 

12-45 

4265.418 

Fe 

24 

1.678 

13-73 

16 

1.464 

13.16 

22 

1.286 

12.82 

18 

i.  06  1 

12.43 

4266.081 

Mn 

24 

1.68? 

13.80 

16 

1-477 

13-27 

23 

1.295 

12.91 

18 

1.078 

12.63 

4268.915 

Fe 

24 

1.676 

13-71 

16 

1.464 

13.16 

22 

1.286 

12.82 

18 

1.059 

12.41 

4276.836 

-Zr 

24 

1.677 

13-72 

16 

1.464 

13.16 

23 

1.281 

12.77 

18 

1.062 

12-44 

4284.838 

Ni 

24 

1.666 

13-63 

16 

1-459 

13.11 

23 

1.282 

12.78 

18 

i.  068 

12.51 

4287.566 

Ti 

24 

1.665 

13.62 

16 

1-459 

13.11 

22 

1.280 

12.76 

18 

1.063 

12-45 

4288.310 

Ti,  Fe 

24 

1.670 

13.66 

16 

1.462 

13-14 

23 

I-27S 

12.71 

18 

1.067 

12.50 

4290.37? 

Ti 

24 

1.661 

13-59 

16 

I-45I 

13-04 

23 

1-275 

12.71 

18 

i.  060 

12.42 

4290.542 

Fe 

24 

1.669 

13-65 

16 

1-457 

13.09 

23 

1.276 

12.72 

18 

1.065 

12.48 

4291.630 

Fe 

24 

1.667 

13.64 

16 

1-459 

13.11 

23 

1.280 

12.76 

18 

1.065 

12.48 

4294-936 

Zr 

24 

1.666 

13-63 

16 

1.462 

13.12 

23 

1.288 

12.84 

18 

i.  068 

12.51 

X 

ELEMKNT. 

*  =  «* 

0  -  65!6 

0  =  75?i 

*  =  8o!4 

4196.699 

La 

22 

0.842 

11.80 

IS 

0.675 

11.65 

33 

0.407 

II.  21 

ii 

•  0.271 

11-54 

4197.257 

CN 

22 

0.848 

11.90 

16 

0.674 

11.63 

33 

0.413 

11.41 

ii 

0.269 

"•4S 

4203-730 

Cr 

24 

0.871 

12.22 

20 

0.692 

it-94 

32 

0.442 

12.20 

ii 

1  0.283 

12.05 

4209-144 

Zr 

24 

0.877 

12.31 

20 

0.698 

12.04 

33 

0.438 

12.09 

ii 

0.280 

11.92 

4216.136 

CN 

24 

0.851 

n-94 

20 

0.673 

11.61 

33 

0.407 

II.  21 

ii 

0.270 

"•49 

4220.509 

Fe 

24 

0.868 

12.17 

2O 

0-693 

11.96 

33 

0.440 

12.15 

ii 

0.286 

12.18 

4232.887 

Fe 

24 

0.873 

12.25 

20 

0.698 

12.04 

33 

0.438 

12.10 

ii 

0.279 

u.88 

4257-8i5 

Mn 

24 

0.883 

12.39 

20 

0.710 

12.25 

33 

0.456 

12-59 

ii 

0.284 

12.09 

4258-477 

Fe 

24 

0.881 

12.36 

2O 

0.698 

12.04 

33 

0.442 

12.  2O 

ii 

0.278 

11.83 

4265-418 

Fe 

24 

0.874 

12.26 

2O 

0.694 

"•97 

33 

0-435 

12.01 

ii 

0-277 

11.79 

4266.081 

Mn 

23 

0.884 

12.40 

20 

0.707 

12.20 

33 

0-452 

12.48 

ii 

0.287 

12.22 

4268.915 

Fe 

24 

0.864 

12.12 

19 

0-703 

12.13 

33 

0.436 

I2.O4 

ii 

0.276 

"•75 

4276.836 

-Zr 

24 

0.869 

12.19 

2O 

0.699 

I  2.  06 

33 

0-435 

I2.OI 

ii 

0.276 

11-75 

4284.838 

Ni 

24 

0.864 

12.12 

20 

0.696 

I2.OI 

33 

0-435 

12.01 

ii 

0.276 

ii-7S 

4287.566 

Ti 

24 

0.874 

12.26 

20 

0.697 

12.02 

33 

0.436 

12.04 

ii 

0.270 

u.88 

4288.310 

Ti,  Fe 

24 

0.866 

12.15 

2O 

0.694 

11.97 

33 

0-437 

12.07 

ii 

0.276 

"-7S 

4290-377 

Ti 

24 

0.858 

12.04 

20 

0.691 

n-93 

33 

0.431 

11.90 

n 

0.269 

11-45 

4290.542 

Fe 

24 

0.856 

12.01 

20 

0.693 

11.96 

33 

0-437 

12.07 

ii 

0.274 

u.66 

4291-630 

Fe 

24 

0.862 

12.09 

2O 

0.699 

I  2.  06 

33 

0.448 

12.37 

ii 

0.276 

"•75 

4294-936 

Zr 

24 

0.870 

12.21 

20 

0.694 

11.96 

33 

0-434 

11.98 

ii 

0.277 

11.79 

OBSERVATIONS    OF    1908.  59 

Since  a  satisfactory  discussion  of  the  preceding  results  involves  a  comparison  with  the  values  obtained 
during  1908,  and  the  addition  of  the  summaries  for  the  latter  at  this  point  would  necessarily  involve  a  large 
amount  of  repetition  and  duplication  of  tables,  it  has  seemed  to  me  preferable  to  undertake  next  the 
detailed  consideration  of  the  1908  observations.  When  these  have  been  brought  to  the  point  at  which  we 
now  leave  the  1906-1907  observations,  we  shall  be  able  to  take  up  the  discussion  of  the  two  simultaneously 
and  carry  them  on  to  advantage  in  parallel  columns.  Accordingly,  we  now  pass  to  a  consideration  of  the 

later  results. 

6.    OBSERVATIONS  or  1908. 

It  was  not  intended  at  the  conclusion  of  the  series  of  observations  made  with  the  Snow  telescope  during 
1906-1907  to  undertake  an  extended  continuation  of  the  work  for  a  considerable  time.  Two  circumstances, 
however,  led  to  a  modification  of  this  plan.  The  first  was  the  completion  of  the  tower  telescope  and  the 
knowledge  we  came  to  have  of  the  decidedly  superior  advantages  possessed  by  it  over  the  Snow  telescope, 
both  as  regards  astigmatism  and  changes  of  focus  of  the  image,  and  the  power  and  efficiency  of  the 
spectroscopic  equipment  used  in  connection  with  it.  The  second  was  the  discovery  of  the  remarkable  dif- 
ferences in  the  period  and  law  of  rotation  of  the  sun  which  are  indicated  when  we  compare  results  given  by 
the  hydrogen  lines  with  those  derived  from  the  ordinary  lines  of  the  general  reversing  layer  (15).  This 
discovery  naturally  made  it  desirable  to  study  certain  special  lines  in  the  spectrum,  and  at  the  same  time 
to  continue  the  study  of  the  rotation  period  for  the  reversing  layer  to  act  as  a  check  on  the  other  results 
found.  Moreover,  such  a  determination,  when  compared  with  the  earlier  one  of  1906-1907,  would  be  of. 
great  value  in  its  bearing  on  the  question  first  raised  by  Halm,  of  a  variation  in  the  sun's  period  of  rota- 
tion. Accordingly,  in  February,  1908,  a  new  series  of  observations  was  begun  with  the  tower  telescope. 

The  essential  features  of  the  tower  telescope  are  a  coelostat  with  a  mirror  17  inches  (43.2  cm)  in  diameter, 
mounted  on  a  track  running  north  and  south,  and  an  elliptical  second  mirror  22.25  x  I2-75  inches  (56.5  x 
32.4  cm)  in  size,  used  in  connection  with  it,  which  sends  the  beam  of  light  received  from  the  ccelostat  upon 
a  i2-inch  (30.5  cm)  visual  objective  immediately  beneath  it.  This  objective  forms  the  image  of  the  sun 
on  the  slit  of  the  spectrograph  60  feet  (18.3  m)  below,  at  a  distance  of  5  feet  (1.5  m)  above  the  level  of  the 
ground.  Two  tracks  are  provided  for  the  ccelostat  on  the  summit  of  the  tower,  the  instrument  being  used 
on  the  west  side  for  observations  during  the  morning  hours,  and  transferred  to  the  east  track  in  the  after- 
noon. Its  position  north  and  south  on  its  track  is,  of  course,  defined  by  the  declination  of  the  sun.  Two 
slow  motions  are  provided  for  controlling  the  position  of  the  image,  the  first  by  means  of  an  electric  motor 
which  rotates  the  ccelostat  mirror  slowly,  and  the  second  by  a  handle  which  turns  the  second  plane  mirror 
about  a  vertical  axis.  The  objective  can  be  focused  by  the  observer  from  near  the  end  of  the  spectro- 
graph, by  means  of  a  steel  tape  and  hand-wheel,  which  moves  the  objective  in  a  vertical  direction. 

Probably  the  most  distinctive  feature  of  this  instrument  is  the  great  thickness  of  the  two  mirrors 
employed.  This  is  the  same  for  both  mirrors  and  amounts  to  12  inches  (30.5  cm),  the  object  being  to 
provide  great  resistance  to  flexure  when  the  surfaces  are  heated  by  exposure  to  sunlight.  Additional 
advantages  tending  to  improve  the  character  of  the  sun's  image,  which  the  tower  telescope  possesses,  are 
the  direction  of  the  beam,  which  is  vertical  instead  of  horizontal,  and  the  fact  that  the  path  of  the  beam, 
due  to  the  formation  of  the  image  by  a  lens,  is  single  instead  of  double,  as  would  be  the  case  with  a  concave 
mirror.  A  fourth  advantage,  which  is  probably  of  great  importance,  is  that  the  light  falls  upon  the  surface 
of  the  ccelostat  mirror  at  an  elevation  of  over  60  feet  above  the  surface  of  the  ground,  and  so  is  free  from 
many  disturbing  effects  suffered  by  light  which  passes  close  to  the  surface  of  the  ground.  As  a  result 
of  these  various  points  of  advantage,  the  character  of  the  image  is  on  the  average  considerably  superior 
to  that  formed  by  the  Snow  telescope,  and  the  effect  of  astigmatism  and  changes  of  focus  is  much  less 
marked.  As  a  rule  the  effect  of  prolonged  exposure  to  sunlight,  at  least  during  the  morning  hours,  is  shown 
by  a  gradual  shortening  of  the  focal  length  indicating  a  tendency  on  the  part  of  the  mirrors  to  become 
slightly  concave  (16).  This  continues  to  some  extent  even  when  the  mirrors  are  covered,  and  it  is  probably 
due  to  the  fact  that  the  edges  of  the  glass  become  heated  from  contact  with  the  warm  air  and  expand  more 


60      AN   INVESTIGATION   OF   THE   ROTATION  PERIOD   OF  THE   SUN    BY   SPECTROSCOPIC   METHODS. 

rapidly  than  the  interior  of  the  glass,  to  which  the  heat  is  conducted  comparatively  slowly.    The  whole 
effect  is  very  gradual,  however,  and  hardly  appreciable  during  exposures  of  half  an  hour. 

The  spectrograph  employed  with  the  tower  telescope  is  of  30  feet  (9.1  m)  focal  length,  and  stands  in  a 
vertical  position  in  an  underground  chamber,  the  walls  of  which  are  lined  with  concrete.  The  spectrograph 
is  of  the  auto-collimating  type  and  consists  of  a  skeleton  steel  tube,  at  the  lower  end  of  which  is  a  heavy 
casting  which  carries  the  lens  and  the  grating  mounting.  The  casting  terminates  in  a  rounded  head  which 
fits  into  a  cup-shaped  support  in  another  casting  attached  to  a  small  pier  on  the  floor  of  the  pit,  and  this 
bearing  carries  practically  the  entire  weight  of  the  spectrograph.  The  top  of  the  instrument  consists  of  a 
large  round  plate  carrying  the  slit  and  plate-holder  supports.  Along  the  outer  edge  of  this  plate  there  is  a 
circle  30  inches  (0.76  m)  in  diameter,  graduated  to  degrees,  and  capable  of  being  estimated  to  within  one- 
tenth  of  that  amount.  The  entire  spectrograph,  including  this  plate,  can  be  rotated  about  a  vertical  axis 
by  means  of  a  rack  and  pinion.  In  order  to  define  the  upper  end  of  the  instrument,  there  is  a  large  sta- 
tionary ring  in  which  the  plate  forming  the  top  of  the  spectrograph  fits  closely.  This  carries  an  index  for 
reading  the  circle  and  also  serves  to  support  some  of  the  slow-motion  handles.  The  lens  and  the  grating 
are  adjusted  by  handles  near  the  slit,  and  the  focus  of  the  former  is  read  by  a  small  telescope. 

The  diagonal-prism  arrangement  used  to  bring  the  images  of  the  opposite  edges  of  the  sun  upon  the 
slit  is  considerably  more  simple  than  that  used  in  the  observations  of  1906-1907.  This  is  due  to  the  fact 
that  since  the  spectrograph  rotates  as  a  whole,  the  attachment  itself  requires  no  provision  for  motion  in 
position  angle,  but  can  be  clamped  directly  to  the  top  of  the  spectrograph.  It  consists  of  a  small  iron 
casting  about  8  inches  (20.3  cm)  high  which  is  fastened  to  the  spectrograph  plate  by  two  taper  pins  The 
lower  surface  of  the  casting  is  a  few  millimeters  above  the  plane  of  the  slit,  and  to  it  are  attached  four  small 
diagonal  prisms,  two  immediately  above  the  slit,  and  two,  at  a  distance  from  each  other  of  approximately 
the  sun's  diameter,  beneath  small  openings  in  the  casting.  The  distance  between  the  first  pair  can  be  varied 
to  allow  for  variations  in  the  size  of  the  sun's  image,  and  the  light  from  them  is  received  by  the  second  pair 
of  prisms  and  reflected  upon  the  slit.  Each  prism  is  mounted  independently  and  provided  with  adjusting 
screws.  The  sun's  image  is  centered  by  means  of  circles  ruled  on  an  aluminium  plate  fastened  to  the  top 
of  the  casting  and  concentric  with  the  center  of  the  slit.  The  faces  of  the  prisms  can  be  cleaned  without 
removing  them  from  their  mountings. 

With  this  form  of  mounting  it  is  evident  that  the  danger  of  changes  in  the  illumination  of  the  grating 
surface  is  much  less  than  in  cases  where  the  diagonal  prisms  themselves  are  movable.  I  have,  however, 
been  careful  to  maintain  the  precautions  used  in  the  earlier  series  and  have  tested  the  character  of  the  illumi- 
nation frequently,  always  before  and  after  the  series  of  exposures,  and  usually  before  some  of  the  inter- 
mediate exposures.  The  margin  of  safety  for  full  illumination  of  the  grating  surface  is  approximately  the 
same  for  this  instrument  as  for  the  spectrograph  used  with  the  Snow  telescope.  The  ratio  of  aperture 
to^focal  length  for  the  tower  telescope  is  i :  60.  The  grating  employed  with  the  spectrograph,  which  is  the 
same  as  that  used  in  the  earlier  series  of  observations,  has  a  ruled  surface  3.25  inches  (8.3  cm)  long.  In  the 
third  order  the  projection  of  this  surface  would  be  less  than  3  inches,  to  fill  which  would  require  a  ratio  of 
i  :  120.  The  factor  of  safety  in  this  case,  accordingly,  is  about  2. 

Since  the  grating  used  in  this  series  of  observations  is  the  same  as  that  of  the  earlier  series,  it  has  been 
possible  to  make  a  direct  comparison  of  the  plates  as  regards  quality  and  definition.  For  these  photo- 
graphs the  third  order  has  been  employed,  as  against  the  fourth  order  previously.  With  a  focal  length  of 
spectrograph  five-thirds  as  great,  however,  there  is  a  gain  in  linear  scale  approximately  in  the  ratio  of  5  :  4. 
More  exactly,  the  linear  scale  of  the  1908  plates  in  the  violet  is  i  mm  =  0.56  Angstrom,  while  for  the  1906 - 
1907  observations  it  is  i  mm  =  0.71  Angstrom.  In  spite  of  this  increase  in  linear  scale  the  lines  are  decid- 
edly superior  on  the  later  plates,  a  result  which  is  to  be  attributed  in  part,  no  doubt,  to  the  fact  that  the 
definition  in  the  third  order  of  this  grating  is  considerably  superior  to  that  in  the  fourth,  but  probably  still 
more  to  the  excellent  conditions  of  temperature  under  which  the  grating  is  working  at  the  bottom  of  the 
deep  underground  chamber.  Experiments  have  shown  that  the  total  variation  at  the  bottom  of  this  pit 


ADAMS 


PLATE  1 


"o 
I 


OBSERVATIONS   OF    1 908. 


6l 


corresponding  to  a  daily  range  inside  the  spectroscope  house  of  about  15°  C.  can  hardly  exceed  o?o6  C. 
It  is  scarcely  possible  that  the  grating  can  have  worked  under  conditions  approaching  this  in  excellence 
when  in  the  horizontal  spectrograph  in  the  Snow  telescope  house.  The  effect  of  small  variations  of  tempera- 
ture in  the  grating  during  an  exposure  will  eventually  be  to  widen  the  lines  slightly  without,  in  the  case  of 
differential  determinations  of  this  sort,  introducing  errors  into  the  displacements,  since  both  spectra  are 
affected  alike.  The  accidental  errors  of  measurement  will,  however,  be  somewhat  greater  for  the  wider 
lines,  and  this  is  no  doubt  partly  accountable  for  the  gain  in  the  internal  agreement  of  the  measures  on  the 
later  plates. 

The  procedure  followed  in  taking  the  plates  differs  little  from  that  used  in  the  earlier  series,  and  so  does 
not  require  very  extended  consideration.  The  fact  that  the  spectrograph  itself  is  rotated  to  obtain  the 
position-angle  settings  for  the  various  latitudes  desired  has  made  it  possible  to  secure  on  all  of  the  plates 
a  position  corresponding  to  the  projection  of  the  sun's  pole  on  its  visible  edge,  and  this  has  been  used  as  a 
most  important  check  on  the  results  for  the  successive  exposures.  It  constitutes  a  very  marked  advantage 
which  the  later  plates  possess  over  those  of  the  earlier  series.  The  reference  line  for  the  observations  is 
obtained  by  securing  the  transits  of  the  sun's  image  across  the  3o-inch  position  circle  on  the  top  of  the  spec- 
trograph, the  instrument,  of  course,  being  brought  to  the  zero  position  before  the  exposures  are  begun. 
Transits  of  both  edges  are  taken  and  the  mean  value  used  for  the  sun's  center.  Three  or  four  separate 
observations  are  usually  made  for  these  determinations  and  the  mean  taken.  As  in  the  observations  with 
the  Snow  telescope,  experiments  have  shown  no  appreciable  difference  in  the  results  obtained  when  the 
ccelostat  mirror  is  rotated,  or  when  the  clock  is  stopped  and  the  image  allowed  to  drift  across  the  circle. 
With  a  knowledge  of  the  east-and-west  line  obtained  in  this  way  the  position  of  the  sun's  pole  is  readily 
found  by  reference  to  a  solar  ephemeris,  and  the  settings  of  the  position  circle  corresponding  to  the  latitudes 
desired  are  then  readily  made.  In  general,  about  the  same  heliographic  latitudes  have  been  observed 
during  the  present  series  as  in  the  series  of  1906-1907.  The  points  at  o°,  15°,  30°,  45°,  60°,  and  75°  are  in 
fact  almost  exactly  comparable.  At  intermediate  points  somewhat  different  latitudes  have  been  employed, 
but  the  normal  positions  are  sufficiently  close  to  each  other  to  make  accurate  comparisons  simple. 

TABLE  8.  —  LINES  OBSERVED  IN  1908.  «*•* 


X 

ELEMENT. 

INTENSITY. 

BEHAVIOR  AT  LIMB. 

4196.699 

La 

2 

Much  weakened. 

4197-257 

CN 

2 

Slightly  weakened. 

4203.730 

Cr 

2 

Strengthened  and  widened. 

4207.566 

CN 

i  N 

Weakened. 

4216.136 

CN 

i 

Weakened. 

4220.509 

Fe 

3 

Slightly  strengthened  and  widened. 

4232.887 

Fe 

2 

Much  strengthened  and  widened. 

4233.328 

Mn 

4 

Much  weakened.     Probably  not  Mn   but  en- 

hanced line  of  Fe. 

4257-8lS 

Mn 

2 

Slightly  strengthened  and  widened. 

4258.477 

Fe 

2 

Much  strengthened  and  widened. 

4265.418 

Fe 

2 

Slightly  weakened. 

4266.081 

Mn 

2 

Slightly  weakened. 

4268.915 

Fe 

2 

Slightly  weakened. 

4276.836 

-Zr 

2 

Weakened. 

4283.169 

Ca 

4 

Strengthened  and  widened. 

4284.838 

Ni 

I 

Slightly  weakened. 

4287.566 

Ti 

I 

Slightly  strengthened  and  widened. 

4288.310 

Ti,  Fe 

I 

Widened. 

4289.525 

Ca 

4 

Probably  slightly  strengthened. 

4290.377 

Ti 

2 

Slightly  weakened.     Enhanced  line  of  Ti. 

4290.542 

Fe 

I 

Slightly  weakened. 

GO 
>•    Si 


62       AN   INVESTIGATION   OF  THE   ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC  METHODS. 


A  few  modifications  have  been  made  in  the  list  of  lines  used  in  the  earlier  investigation,  with  a  view 
to  the  inclusion  of  certain  lines  of  especial  interest  and  the  omission  of  some  lines  in  the  previous  list  which 
have  no  particular  significance.  The  revised  list  consists  of  the  22  lines  given  in  Table  8. 

Of  the  new  lines  in  the  list,  \  4207.566  is  included  because  of  its  identification  in  Rowland's  table  as 
carbon  (more  accurately  cyanogen).  The  appearance  of  the  line  under  high  dispersion,  however,  indicates 
that  it  is  almost  certainly  of  compound  origin,  and  a  similar  conclusion  is  warranted  by  the  size  of  its 
displacement  at  the  sun's  limb.  The  line  X  4233.328  is  of  great  interest  becauseof  being  a  very  strong  spark, 
or  enhanced,  line  of  iron  and  very  prominent  in  the  spectrum  of  the  chromosphere.  Two  lines  of  calcium 
are  added  to  the  list  for  comparison  with  the  so-called  "blue  line"  at  X  4227,  as  well  as  with  other  lines 
in  the  less  refrangible  part  of  the  spectrum  investigated  by  M.  Perot  by  interference  methods  (17). 
Further  reference  will  be  made  to  these  results  in  the  course  of  the  discussion. 

7.    RECORD  OF  OBSERVATIONS,  1908. 

The  details  of  the  observations  given  in  Table  9  are  taken  from  the  observing  journal  and  cover  the 
33  plates  used  in  this  investigation.  The  table  is  essentially  the  same  as  that  given  for  the  plates  of  1906- 
1907,  the  principal  difference  being  that  in  the  present  series  I  have  measured  the  diameter  of  the  image  and 
the  distance  of  the  slit  inside  the  sun's  limb  directly,  instead  of  computing  them  as  in  the  previous  case. 
The  columns  giving  these  values  are  found  in  the  table  immediately  preceding  the  column  containing  the 
observations  for  zero.  The  use  of  a  lens  instead  of  a  concave  mirror,  as  in  the  case  of  the  Snow  telescope, 
has  of  course  involved  a  correction  in  focusing  the  image  on  the  slit  of  the  spectrograph.  This  is  readily 
found  from  the  shape  of  the  color  curve  for  the  lens,  and  it  has  been  my  practice  before  beginning  the  ob- 
servations to  focus  the  image  on  the  slit  and  then  displace  the  lens  by  an  amount  corresponding  to  this 
difference  for  the  region  under  investigation.  The  other  columns  in  the  table  are  self-explanatory. 

TABLE  9.  —  RECORD  OF  OBSERVATIONS,  1908. 


DATE. 

HOUR 
G.M.T. 

PLATE 
No. 

DEFI- 
NITION. 

EX- 
POSURE 

TIME. 

SLIT 

WIDTH. 

DISTANCE 

INSIDE 
LIMB. 

DIAME- 
TER OF 

IMAGE. 

OBSERVATIONS 

FOR    ZERO. 

EX- 
POSURE. 

READINGS 
POSITION 

CIRCLE. 

igo8 

h     m 

sec 

mm 

mm 

mm 

Feb.  16 

II    10 

w  103 

4 

210 

0.038 

0.5 

172.4 

142.1!      (322.0 

i 

42.8 

168.3  1    \  348.2 

2 

27.8 

3 

12.8 

4 

357-8 

5 

342.8 

6 

327.8 

7 

312.8 

Mar.  10 

7     o 

ta  105 

5 

1  80 

0.045 

3-6 

171.6 

26.5  \    f  206.9 

i 

74-6 

52.3)     1232.8 

2 

59-6 

3 

44.6 

4 

29.6 

S 

14.2 

6 

358-3 

7 

344-6 

8 

343-9 

9 

357-4 

10 

13.0 

ii 

28.7 

Mar.  10 

7  5° 

w  106 

5 

ISO 

0.045 

3.6 

171.6 

1 

i 

AT,  Q 

/ 

2 

*to-y 
58-9 

4 

73-9 

S 

58.9 

6 

43-9 

7 

28.7 

8 

13-0 

9 

357-4 

10 

343-9 

RECORD   OF   OBSERVATIONS,    1908. 
TABLE  9.  —  RECORD  OF  OBSERVATIONS,  1908  —  Continued. 


DATE. 

HOUR 
G.  M.  T. 

PLATE 
No. 

DEFI- 
NITION. 

EX- 
POSURE 

TIME. 

SLIT 

WIDTH. 

DISTANCE 

INSIDE 
LIMB. 

DIAME- 
TER OF 

IMAGE. 

OBSERVATIONS 

FOR   ZERO. 

EX- 
POSURE. 

READINGS 
POSITION 

CIRCLE. 

1908 

h     m 

sec 

mm 

mm 

mm 

0                                             O 

0 

April  8 

7  45 

o  113 

2-3 

180 

0.030 

3.6 

171.6 

43-4  \_l  223.5 
69.5  j      \  249.4 

i 

2 

330.1 
343-1 

3 

358.8 

4 

15.0 

5 

30.1 

(> 

45-1 

7 

60.  i 

May  26 

12       0 

w  117 

4 

90 

0.030 

1.6 

168.7 

297.0  \     f  116.5 

i 

274.2 

271.2)     \    90.8 

2 

287.7 

3 

303-2 

4 

319.0 

S 

334-* 

6 

349-2 

7 

364-2 

8 

364-2 

9 

349-2 

10 

334-2 

ii 

319.0 

12 

303-2 

13 

287.7 

June  2 

3   10 

W    I  2O 

4 

1  20 

0-033 

1.2 

168.0 

61.6  )      /  242.5 
.87.5  f  "   I  268.3 

I 

2 

312.7 
326.2 

3 

341-7 

4 

357-2 

5 

12.7 

(> 

27.7 

7 

42.7 

8 

40.7 

9 

25-7 

10 

10.7 

ii 

355-2 

12 

339-7 

13 

324.2 

14 

310.7 

June  9 

12    SO 

u  128 

2 

105 

0.033 

i-5 

166.0 

269.3  \_1   88.6 
294.  7  j     \H4.i 

I 

2 

270.9 
285-9 

Taken  at  ioh  ism 

3 

300.9 

4 

3I5-9 

5 

330-9 

6 

345-9 

7 

o-9 

June  10 

8  IS 

<•>  132 

2 

90 

0-033 

1.4 

165.6 

62.7  \     I  243-0 
88.4  /    \  268.6 

i 

2 

296.6 
306.6 

Taken  at  3"  om 

3 

321.6 

4 

336.6 

S 

351.6 

6 

6.6 

7 

21.6 

June  ii 

j    ^ 

w  134 

4 

90 

0.033 

2-5 

1  68.0 

62.91      (243.6 
88.6  f     1269.3 

i 

2 

295.8 
305.8 

3 

320.8 

4 

335-8 

5 

350.8 

6 

5-8 

7 

20.8 

8 

25.8 

Tune  i  i 

4    CO 

W  I  7  C 

7C 

O  O3? 

2.1 

167.4 

i 

295.8 

5° 

/o 

•'•'-'OO 

*"/  **t 

2 

305.8 

3 

310.8 

4 

325.8 

5 

340.8 

6 

355.8 

7 

10.8 

8 

2S-8 

64     AN   INVESTIGATION  OF  THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 

TABLE  9. —  RECORD  OF  OBSERVATIONS,  1908  —  Continued. 


DATE. 

HOUR 
G.  M.T. 

PLATE 
No. 

DEFI- 
NITION. 

EX- 
POSURE 

TIME. 

SLIT 

WIDTH. 

DISTANCE 

INSUJE 
LIMB. 

DIAM- 
ETER OF 

IMAGE. 

OBSERVATIONS 

FOR    ZERO. 

EX- 
POSURE. 

READINGS 
POSITION 

CIRCLE. 

igog 

h    m 

sec 

mm 

mm 

mm 

0                                              0 

0 

June  ii 

4  5° 

j  9  f 

7 

7C 

O  032. 

2.1 

167  4 

i 

25°8 

* 

O 

/  J 

*w/  -^ 

2 

10.8 

3 

355-8 

4 

340.8 

5 

325-8 

6 

310.8 

7 

305-8 

8 

295.8 

June  ii 

5  40 

w  136 

2 

80 

O.O32 

i.S 

167.0 

i 

295.8 

""*«J  — 

2 

305-8 

3 

320.8 

4 

335-8 

5 

350.8 

6 

5-8 

7 

20.8 

8 

25.8 

Aug.  5 

9  So 

w  146 

4 

5° 

0.038 

i-3 

1  68.6 

277.1  )    1  96.8 

i 

327.8 

302.7  1     1  122.5 

2 

342.8 

3 

357-8 

4 

'3-3 

5 

28.8 

6 

44-3 

7 

57-8 

Aug.  5 

10  30 

w  147 

3 

7° 

0.038 

1.4 

1  68.6 

i 

57.8 

2 

.  J  / 

44-3 

3 

28.8 

4 

13-3 

5 

357-8 

6 

342.8 

' 

7 

327.8 

Aug.  5 

10  30 

w  148 

3 

7° 

0.038 

1.4 

168.6 

i 

527  8 

2 

o    1  •*•' 

342.8 

3 

357-8 

4 

13-3 

5 

28.8 

6 

44-3 

7 

57-8 

Aug.  6 

5  15 

u  151 

3 

70 

0.038 

i.s 

168.6 

56.2  \    f  236.7 

i 

278.4 

82.0  1     1  262.4 

2 

291.9 

3 

307-7 

4 

323-2 

5 

338.4 

6 

353-4 

7 

8.4 

Aug.  26 

II       0 

ui6i 

3 

75 

0.034 

i.i 

168.9 

JOS-1  I     }  3"-7 

i 

42.1 

131.1  1      I  285.8 

2 

17.7 

3 

1.7 

4 

346.3 

5 

33i-i 

6 

323-6 

7 

316.1 

Aug.  26 

II       O 

l»  162 

3 

75 

0.034 

i.i 

168.9 

i 

316.  i 

2 

o 

3 

331.1 

4 

346.3 

5 

1.7 

6 

17.7 

7 

42.1 

RECORD   OF   OBSERVATIONS,    1908. 
TABLE  9.  —  RECORD  or  OBSERVATIONS,  1908  —  Continued. 


DATE. 

HOUR 
G.  M.  T. 

PLATE 
No. 

DEFI- 
NITION. 

EX- 
POSURE 

TIME. 

SLIT 

WIDTH. 

DISTANCE 

INSIDE 
LIMB. 

DIAME- 
TER OF 
IMAGE. 

OBSERVATIONS 

FOR  ZERO. 

EX- 
POSURE. 

READINGS 
POSITION 
CIRCLE. 

1908 

h      m 

sec 

f  mm 

mm 

mm 

e                           o 

e 

Aug.  26 

II    55 

w  163 

3 

90 

0.0^4. 

I.I 

168.0 

i 

42.1 

*"*'1J*T 

**  y 

2 

17-7 

3 

i-7 

4 

346.3 

S 

33I-I 

6 

323-6 

7 

316.1 

Aug.  26 

II    S5 

w  164 

•3 

oo 

O.O^d 

I.I 

168.9 

i 

316.  i 

O  J 

o 

yw 

""""J"? 

Awu.y 

2 

J»  V 

323-6 

3 

331-1 

4 

346.3 

S 

i-7 

6 

17.7 

7 

42.1 

Aug.  27 

6  45 

u  165 

3 

70 

0.030 

1.6 

168.8 

46.01         f253.2 

72.4  /     (226.8 

i 

2 

280.6 
305.0 

3 

320.9 

4 

336.4 

S 

3Si-6 

6 

359-1 

7 

6.6 

Aug.  27 

6    A< 

u>  1  66 

•3 

7O 

O.O^O 

1.6 

168.8 

i 

6.6 

*to 

O 

/  v 

V>VJW 

2 

359-1 

3 

351-6 

4 

336.4 

S 

320.9 

6 

305-0 

7 

280.6 

Sept.  30 

II  40 

<•>  179 

3 

90 

0.038 

I.O 

170.6 

I24-7\_/  3°4-6 

5 

45-5 

150.8  (     1330.7 

6 

45-5 

Taken  at  ioh  35™ 

Sept.  30 

II  40 

w  180 

3 

90 

0.038 

I.O 

170.6 

3 

45-S 

4 

45-5 

Oct.  9 

II       0 

o>  182 

4 

90 

0.038 

I.O 

170.6 

130-4  \     I  310-2 

S 

3I4-2 

156.6  (     1336-4 

6 

3I4-2 

7 

299.2 

8 

291.2 

Oct.  9 

II       O 

w  183 

A 

ne 

0.0^8 

I.O 

170.6 

i 

291.2 

t 

yj 

ta"^'O 

2 

299.2 

3 

314-2 

4 

3I4-2 

S 

299.2 

6 

291.2 

7 

291.2 

8 

299.2 

Oct.  22 

6  30 

w  184 

4 

140 

0.041 

1-3 

171.2 

'QS-Sl/    iS-9 
221.8  /     \   42.3 

i 

2 

305-1 
329.1 

3 

334-4 

4 

344-8 

S 

344-8 

6 

334-4 

7 

329-1 

8 

3i-i 

Oct.  22 

6  ^o 

w  185 

4. 

I4O 

0.041 

I.  a 

171.2 

i 

SI.I 

v    ,jw 

*T 

**TN^ 

•  'j 

2 

329.1 

4 

344-8 

S 

344-8 

7 

329-1 

Oct.  22 

7    4S 

01  186 

•3 

I4O 

0.041 

I.O 

171.2 

i 

329.1 

/     *r  J 

O 

•LtfW 

3 

344-8 

4 

3i-i 

S 

3i-i 

8 

329.1 

66      AN   INVESTIGATION  OF   THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 


The  plates  used  in  this  investigation  have  been  measured  on  the  same  instruments  as  those  of  the  earlier 
series,  and  accordingly  the  previous  discussion  of  the  screw  errors  of  these  comparators  is  directly  appli- 
cable in  the  present  work.  The  process  of  measurement  has  also  been  identical  in  the  two  cases  as  well  as 
the  combination  of  the  individual  determinations  to  form  the  final  means.  In  the  present  series  the  inclina- 
tion of  the  micrometer  wire  in  the  measuring  comparator,  determined  by  means  of  a  plate  taken  with  a 
long  slit,  is  controlled  by  the  exposure  secured  on  the  pole  of  the  sun.  The  conversion  of  the  measured 
displacements  into  linear  velocity  is  made  by  means  of  Table  10,  which  is  very  similar  to  that  given  for  the 
earlier  observations,  and  differs  from  it  only  because  of  the  difference  in  the  linear  scale  of  the  plates.  The 
quantities  correspond  to  the  displacements  measured  with  the  Toepfer  comparator  in  units  of  the  half- 
millimeter. 

TABLE  10.  • —  CONVERSION  OF  DISPLACEMENTS  INTO  VELOCITIES.    OBSERVATIONS  OF  1908. 


X 

ONE  REVOLUTION 
IN  ANGSTROMS. 

ONE  ANGSTROM 

IN  KM. 

ONE-HALF 
REVOLUTION 

IN  KM. 

X 

ONE  REVOLUTION 
IN  ANGSTROMS. 

ONE  ANGSTROM 

IN  KM. 

ONE-HALF 
REVOLUTION 

IN  KM. 

4196.699 

0.2996 

71-45 

IO.7O 

4266.081 

0.2984 

70.29 

10.49 

4197-257 

0.2996 

71.44 

IO.7O 

4268.915 

o.  2984 

70.24 

10.48 

4203.730 

0.2995 

71-33 

10.68 

4276.836 

0.2984 

7O.II 

10.46 

4207.566 

0.2994 

71.27 

10.67 

4283.169 

0.2982 

7O.OI 

10.44 

4216.136 

0.2992 

71.12 

10.64 

4284.838 

0.2982 

69.98 

10.43 

4220.509 

0.2992 

71-05 

10.63 

4287.566 

0.2982 

69.94 

10.43 

4232.887 

0.2988 

70.84 

10.58 

4288.310 

0.2982 

69.92 

10.43 

4233-328 

0.2988 

70.83 

10.58 

4289.525 

0.2982 

69.90 

10.42 

4257-815 

0.2986 

70-43 

10.52 

4290.377 

0.2982 

69.89 

10.42 

4258.477 

0.2986 

70.42 

10.51 

4290.542 

0.2982 

69.89 

10.42 

4265.418 

0.2984 

70.30 

10.49 

4291.630 

0.2982 

69.87 

10.42 

It  is  unnecessary  to  consider  further  the  various  corrections  to  be  applied  to  the  observed  linear  veloci- 
ties to  reduce  them  to  the  sun's  sidereal  period  of  rotation,  or  the  computation  of  the  latitudes,  since  the 
process  of  obtaining  these  is  identical  with  that  used  in  the  previous  reductions. 

Two  important  respects  in  which  the  observations  of  1908  have  a  marked  advantage  over  those  in  the 
earlier  series  have  been  referred  to  in  the  course  of  the  description  of  the  instrument.  The  first  of  these  is 
in  the  quality  of  the  sun's  image  formed  by  the  object-glass  of  the  telescope,  and  its  comparative  freedom 
from  astigmatism  and  changes  of  focus  during  the  exposures  taken  upon  the  plates.  The  importance  of 
this  source  of  error  was  dwelt  upon  strongly  in  the  previous  discussion  of  this  subject,  and  the  probability 
that  it  is  largely,  if  not  wholly,  eliminated  in  the  case  of  the  tower  telescope  can  not  fail  to  be  of  the  greatest 
possible  value  to  the  results  obtained.  The  second  advantage  is  in  the  relative  stability  of  the  diagonal- 
prism  apparatus,  which  forms  the  images  upon  the  spectrograph  slit,  and  upon  which  the  illumination  of 
the  grating  depends.  With  the  precautions  taken  in  the  first  series  of  observations  considerable  changes 
of  illumination  could  hardly  have  escaped  detection,  but  sufficiently  small  changes  might  have  done  so, 
and  accordingly  it  is  a  source  of  decided  satisfaction  that  in  the  present  series  of  determinations  the  danger 
of  error  from  this  source  is  also  greatly  reduced.  A  third  important  consideration  has  already  been  referred 
to,  but  may  well  be  emphasized  again.  This  is  the  presence  on  each  plate  of  a  spectrum  of  the  edge  of  the 
sun  corresponding  to  the  projection  of  the  pole.  This  furnishes  a  practical  check  on  all  of  the  adjustments 
of  the  instrument  of  the  type  so  much  to  be  desired  in  the  measurement  of  small  displacements. 

8.    RESULTS  FOR  THE  INDIVIDUAL  PLATES,  1908. 

The  results  for  the  individual  plates  are  given  in  Table  n  in  the  same  form  as  in  Table  4  for  the  earlier 
observations,  and  the  symbols  employed  are  the  same  throughout.  The  sole  difference  in  the  constants 
of  reduction  used  is  that  the  value  of  the  longitude  of  the  ascending  node  of  the  sun's  equator  fl,  has  been 
modified  by  a  slight  correction  corresponding  to  the  precession  for  the  two  years  intervening  between  the 
two  sets  of  observations.  The  value  employed  is  74°  26'. 


RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1908. 


67 


TABLE  ii.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908. 
Plate  u  103.     1908,  Feb.  16,  nh  iom  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  0.5  mm.    Quality,  good. 

p  —  P  7T  0  7)  S6CJ) 


0.2 

Q       326.9 

14.8 

16.3 

73-7 

25-4 

1.107 

O-fi     252.4 

29.8 

30-5 

59-5 

13-7 

1.029 

P         17.8 

44.8 

45-2 

44.8 

9.8 

i.  015 

D        -6.9 

59-8 

60.  i 

29.9 

8.0 

I.OIO 

Diameter  172.4  mm 

74.8 

74-9 

14.1 

7.2 

1.008 

Factor        1.014 

89.8 

90.2 

—  O.2 

6.9 

1.007 

*. 

-«:, 

*- 

* 

0- 

.A 

A 

V 

.+,, 

• 

A 

V 

.  +  „ 

6 

A 

V 

.  +  ., 

« 

4196.699 

0.177 

km 
1-935 

km 
2.077 

14-75 

0.165 

km 

1-805 

km 
1.944 

14-23 

0.138 

km 
1.512 

km 
1.636 

13-40 

4197-257 

0.178 

1-945 

2.087 

14.82 

0.165 

1.805 

1.944 

14-23 

0.138 

I.5I2 

1.636 

I3-40 

4203.730 

0.176 

1.920 

2.062 

14.64 

o.i  66 

I.8lO 

1.949 

14.27 

0.140 

I-53I 

1-655 

13-55 

4207.566 

0.177 

1.928 

2.070 

14.70 

o.i  68 

1.826 

1.965 

14-38 

0.140 

1-542 

1.666 

13.64 

4216.136 

0.178 

1-935 

2.077 

H-75 

0.169 

1.838 

1.977 

14.47 

0.139 

I-5I4 

1.638 

I3-4I 

4220.509 

0.180 

1-954 

2.096 

14.88 

o.i  68 

.827 

1.966 

14-39 

0.140 

I-54I 

1.665 

13.64 

4232.887 

0.180 

1.946 

2.088 

14.83 

0.170 

.841 

1.980 

14.49 

0.142 

1-538 

1.662 

13.61 

4233.328 

0.177 

1-913 

2-055 

14-59 

0.170 

.840 

1.979 

14-49 

0.140 

1.518 

1.642 

13-45 

4257-815 

0.183 

1.965 

2.107 

14.96 

0.172 

•845 

1.984 

14-52 

0.142 

1.528 

1.652 

13-53 

4258.477 

0.179 

1.922 

2.064 

14-65 

0.171 

.835 

•974 

14-45 

0.140 

1.504 

1.628 

13-33 

4265.418 

0.180 

1.928 

2.070 

14.70 

0.167 

.787 

.926 

14.10 

0.140 

I.S03 

1.627 

I3-32 

4266.081 

0.182 

1.950 

2.092 

H.85 

0.171 

.832 

.971 

14-43 

0.144 

1.546 

1.670 

13.68 

4268.915 

0.180 

1.926 

2.068 

14.69 

o.i  68 

.796 

•935 

14.16 

0.137 

1.470 

1-594 

13-05 

4276.836 

0.182 

•945 

2.087 

14.82 

o.i  68 

•795 

•934 

14-15 

0.142 

I.5I7 

1.641 

13-44 

4283.169 

0.178 

.898 

2.040 

14.48 

0.169 

.801 

•940 

14.20 

0.142 

I-5I7 

1.641 

13-44 

4284.838 

0.180 

.920 

2.062 

14.64 

0.171 

.821 

.960 

14-35 

0.140 

1-497 

1.621 

13.28 

4287.566 

0.181 

.927 

2.069 

14.70 

0.169 

.800 

•939 

14-19 

0.142 

I-5I5 

1.639 

I3-42 

4288.310 

0.182 

•939 

2.081 

14.78 

0.167 

.782 

.921 

14.06 

0.142 

I-SI5 

1.639 

13-42 

4289.525 

0.180 

.917 

2.059 

14.62 

o.i  66 

•770 

.909 

13-97 

0.140 

1-495 

1.619 

13.26 

4290.377 

0.180 

.916 

2.058 

14.61 

0.165 

.760 

.899 

13-90 

0.138 

1.472 

1.596 

13.07 

4290.542 

0.180 

•915 

2.057 

14.60 

0.167 

.780 

.919 

14.05 

0.141 

1.504 

1.628 

13-33 

4291.630 

0.179 

•905 

2.047 

14-53 

0.170 

.809 

.948 

14.26 

0.136 

1-454 

1.578 

12.92 

0  = 

44!8 

0  = 

sts 

0  = 

73!? 

4196.699 

0.108 

1.189 

1.294 

12.94 

0.060 

0.670 

0.746 

10.44 

0.030 

0.360 

0.402 

10.17 

4197-257 

0.108 

1.189 

1.294 

12.94 

0.060 

0.670 

0.746 

10.44 

0.032 

0.384 

0.426 

10.78 

4203.730 

0.109 

1.198 

I-303 

13-03 

0.062 

0.690 

0.766 

10.71 

0.034 

0.407 

0.449 

11.36 

4207.566 

0.109 

1.191 

1.296 

12.96 

0.062 

0.689 

0.765 

10.70 

0-035 

0.419 

0.461 

11.66 

4216.136 

0.108 

1.178 

1.283 

12.83 

0.062 

0.689 

0.765 

10.70 

0.034 

0.406 

0.448 

"•33 

4220.509 

0.108 

1.178 

1.283 

12.83 

0.062 

0.687 

0.763 

10.67 

0.032 

0.382 

0.424 

10.73 

4232.887 

0.108 

1.176 

1.281 

12.81 

0.064 

0.703 

0-779 

10.90 

0.034 

0.404 

0.446 

11.28 

4233-328 

O.IIO 

1.198 

I-303 

13-03 

0.062 

0.684 

0.760 

10.63 

0.032 

0.380 

0.422 

10.67 

4257-815 

O.II2 

1.192 

1.297 

12.97 

0.066 

0.723 

0.779 

ii.  18 

0-035 

0.413 

0-455 

11.51 

4258.477 

0.108 

1.168 

1-273 

12.73 

0.065 

0.713 

0-789 

11.04 

0.032 

0-377 

0.419 

10.60 

4265.418 

O.I  1  1 

1.182 

1.287 

12.87 

0.065 

0.711 

0.787 

II.OI 

0.032 

0-377 

0.419 

10.60 

4266.081 

O.IIO 

1.183 

1.288 

12.88 

0.064 

0.700 

0.776 

10.85 

0.034 

0.401 

0-443 

II.  21 

4268.915 

O.IIO 

1.182 

1.287 

12.87 

0.065 

0.709 

0.785 

10.98 

0.034 

0.400 

0.442 

11.18 

4276.836 

O.I  I  I 

1.192 

1-297 

12.97 

0.064 

0.699 

0-775 

10.84 

0.034 

0.400 

0.442 

ii.  18 

4283.169 

O.IIO 

1.181 

1.286 

12.86 

0.066 

0.719 

0-795 

II.  12 

0.032 

0-375 

0.417 

10.55 

4284.838 

O.IIO 

1.183 

1.288 

12.88 

0.066 

0.718 

0-794 

II.  II 

0-035 

0.410 

0.452 

"•43 

4287.566 

O.II2 

1.208 

I-3I3 

I3-I3 

0.064 

0.698 

0-774 

10.83 

0-035 

0.410 

0.452 

"•43 

4288.310 

O.II2 

1.208 

I-3I3 

I3-I3 

0.066 

0.717 

0-793 

II.O9 

0.034 

0.398 

0.440 

"-13 

4289.525 

O.IIO 

1.181 

1.286 

12.86 

0.064 

0.697 

0-773 

I0.8I 

0.036 

0.421 

0.463 

11.71 

4290.377 

0.108 

I-I57 

1.262 

12.62 

0.062 

0.674 

0.750 

10-49 

0.034 

0.398 

0.440 

11.13 

4290.542 

0.108 

1.158 

1.263 

12.63 

0.065 

0.706 

0.782 

10-94 

0.036 

0.421 

0.463 

11.71 

4291.630 

O.IIO 

1.179 

1.284 

12.84 

0.064 

0.696 

0.772 

10.80 

0.034 

0.398 

0.440 

11.13 

68      AN   INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  iosr     1908,  March  10,  7h  om  G.  M.  T.     Measured  by  A.  on  G.     Distance  from  Limb  1.8  mm      Quality,  good. 


P-f 


secy 


Q 

O-Si 
P 
D 


349-8 

275-3 

23-9 

-7.2 


Diameter  171.6  mm 
Factor        1.021 


0.3 

14.0 

15-7 

74-3 

27.7 

.129 

29.9 

3°-7 

59-3 

14.2 

.032 

45-3 

45-8 

44.2 

IO.I 

.016 

60.3 

60.6 

29.4 

8-3 

.on 

75-3 

75-4 

14.6 

7-4 

.008 

9°-3 

9°-3 

-  °-3 

7.2 

.008 

\ 

0  =  -  o!3 

0    =    14^6 

0  -  29!4 

0  =  44!2 

A 

A 

• 

,  +  „ 

» 

A 

• 

,  +  „ 

I 

A 

1! 

,  +  „ 

* 

A 

• 

,-M, 

i 

4196.699 

0.170 

km 

1.  880 

km 

2.O2O 

14-31 

0.170 

km 

1.  880 

km 
2.016 

14.79 

0.136 

km 
1.508 

km 
.631 

13-29 

O.III 

km 
1-237 

km 
1-338 

13-25 

4197-257 

0.170 

1.880 

2.O2O 

14-31 

o.i  68 

1.814 

1.950 

14-31 

0.132 

1-463 

•586 

12.92 

O.II2 

1.248 

1-349      I3-36 

4203.730 

0.176 

1.942 

2.082 

14-77 

o.i  68 

1-854 

1.990 

14.60 

0.136 

I.505 

.628 

I3-27 

O.I  I  2 

1-245 

I-346      13-33 

4207.566 

o.i  68 

1.852 

1.992 

14.14 

0.170 

1.874 

2.OIO 

14.74 

0.132 

1-459 

.582 

12.89 

O.IIO 

1.  221 

1.322      13.09 

4216.136 

0.172 

1.890 

2.030 

14-39 

0.168 

1.848 

1.984 

14-55 

0.128 

1.410 

•533 

12.49 

0.108 

I.I97 

1.298!     12.85 

4220.509 

0.172 

1.889 

2.O29 

14-38 

o.i  68 

1.846 

1.982 

14-53 

0.139 

1.419 

.642 

13-37 

0.113 

1.239 

•340 

13-27 

4232-887 

0.176 

1.924 

2.064 

14.64 

0.172 

1.881 

2.017 

14.80 

0.136 

1.492 

-615 

I3.I6 

O.IIO 

1.  212 

.313 

13.00 

4233-328 

0.172 

1.881 

2.O2I 

14-32 

0.168 

1.836 

1.972 

14.47 

0.136 

1.492 

-615 

13.16 

O.IIO 

1.  212 

•313 

13.00 

4257-815 

0.180 

1-955 

2.095 

14.87 

0.172 

1.869 

2.OO5 

14.71 

0.140 

I.525 

.648 

13-43 

0.118 

.292 

•393 

13.80 

4258.477 

0.176     1.912 

2.052 

14-55 

0.172 

1.869 

2.005 

14.71 

0.142 

1.548 

.671 

13.62 

0.116 

.271 

•372 

13-58 

4265.418 

0.174 

1.886 

2.026 

14.41 

0.172 

1.865 

2.001 

14.68 

0.138 

1.500 

.623 

I3-23 

0.116 

.268 

•369 

13-55 

4266.081 

0.178 

1.930 

2.070 

14.69 

o.i  68 

1.821 

r-957 

14-36 

0.136 

1.476 

•599 

13.02 

O.I  I  2 

.223 

•324 

13.11 

4268.915 

0.180 

1.949     2.089 

14-83 

0.174 

1.884 

2.  02O 

14.82 

0.140 

1.520 

•643 

13-37 

0.116 

.266 

•367 

13-53 

4276.836 

0.180!    1.945]    2.085     14.80 

0.172 

1.858 

•994 

14.63 

0.146 

1.582 

•70S 

13.89 

0.114 

.241 

•342 

13-29 

4283.169 

0.180 

1.941]    2.081 

14-77 

0.172 

1.854 

•990 

14.60 

0.140 

I-5I3 

•636 

1340 

0.116 

.260 

.361 

13-47 

4284.838 

0.180 

1.941 

2.081 

14-77 

0.172 

1.854 

.990 

14.60 

0.136 

1.470 

•593 

12.99 

O.I  I  2 

.217 

.318 

13-05 

4287.566 

0.180 

1.940 

2.O8O 

14.76 

o.i  68 

1.810 

•946 

14.28 

0.144 

I-556 

.679 

I3-65 

0.117 

.270 

•371 

13-57 

4288.310 

0.178 

1.917 

2.057 

14-59 

0.172 

1.852 

.988 

14.58 

0.140 

1.512 

•635 

I3-32 

0.116 

•259 

•360 

13-46 

4289.525 

0.180 

1-939 

2.079 

14-75 

0.172 

1.852 

.988 

14-58 

0.144 

1-554 

.677 

I3-63 

0.118 

.280 

•381 

13-67 

4290.377 

0.176 

1.894 

2.034 

14.42 

0.172 

1.852 

.988 

14.58 

0.140 

1.511 

1-634 

I3-3I 

0.108       .172 

.273 

12.59 

4290.542 

0.180 

1.938 

2.078 

14.74 

o.i74 

1.872 

2.008 

14-73 

0.144 

1-554 

1.677 

13-63 

0.119       .291 

•392 

13-78 

4291.630 

0.184 

1.960 

2.IOO 

14.91 

0.170 

1.830 

1.966 

14-43 

0.146 

I-576 

1.699 

I3-84 

0.116 

1-259 

.360 

13.46 

0  =  S9°3 

0  =  74!3 

0  =  -°°3* 

0  =  i4?6* 

4196.699 

0.066 

0.749 

0.820 

11.40 

0.029 

0.372 

0.408 

10.70 

0.173 

1.909 

2.049 

14-54 

0.163 

1.800 

1.936 

14.21 

4197-257 

0.070 

0-794 

0.865 

12.03 

0.029 

0.372 

0.408 

10.70 

0.177 

1-952 

2.092 

14.86 

0.164 

1.809 

1-945 

14.28 

4203.730 

0.070 

0.790 

0.861 

11.97 

0.031 

0.398 

0-434 

"•39 

0.177 

•948 

2.088 

14.83 

0.165 

1.816 

1-952 

14.33 

4207.566 

0.060 

0-745 

0.816 

"•35 

0.027 

0.346 

0.382 

IO.O2 

0.176 

•936 

2.076 

14-74 

o.i  66 

1.825 

1.961 

14-39 

4216.136 

0.068 

0.765 

0.836 

11.63 

0.028 

0.356 

0.392 

10.28 

0.178 

•952 

2.092 

14.86 

o.i  68 

1.843 

1-979 

14-52 

4220.509 

0.070 

0.787 

0.858 

"•93 

0.033 

0.418 

0-454 

11.91 

0.179 

.960 

2.IOO 

14.90 

0.167 

1.829 

1.965 

14.42 

4232.887 

0.068 

0.763 

0.834 

1  1.  60 

0.031 

0-394 

0.430 

11.28 

0.178 

•942 

2.082 

14.78 

0.168 

1.832 

1.968 

14.44 

4233-328 

0.066 

0.741 

0.812 

11.29 

0.028 

0-355 

0.391 

IO.26 

0.178 

.942 

2.082 

14.78 

0.170 

1.854 

1.990 

14.61 

4257-815 

0.072 

0.802 

0.873 

12.14 

0.032 

0.402 

0.438 

11.49 

0.182 

•973 

2.II3 

I5.OO 

0.172 

1.863 

1.999 

14.67 

4258.477 

0.068 

0.758 

0.829 

"•53 

0.028 

0-342 

0.378 

9.92 

0.179 

.940 

2.080 

14.76 

0.173 

1.874 

2.010 

14-75 

4265.418 

0.072 

0.800 

0.861 

11.97 

0.032 

0.414 

0.450 

n.8i 

0.177 

.914 

2-054 

14-57 

0.169 

1.827 

1.963 

14.41 

4266.081 

0.068 

0.756 

0.827 

11.50 

0.032 

0.414 

0.450 

11.81 

0.180 

.946 

2.086 

I4.8l 

0.173 

1.869 

2.OO5 

14.72 

4268.915 

0.070 

0.778 

0.849 

11.81 

0-035 

0.451 

0.487 

12.78 

0.180 

•944 

2.084 

14-79 

0.169 

1.823 

1-959 

14-37 

4276.836 

0.072 

0.798 

0.869 

12.08 

0.032 

0.412 

0.448 

"•75 

0.181 

•951 

2.091 

14.85 

0.170 

1.832 

1.968 

14.44 

4283.169 

0.072 

0.796 

0.867 

12.05 

0.030 

0.390 

0.426 

11.  18 

0.180 

•936 

2.076 

14-74 

0.172 

1.849 

1-985 

14-59 

4284.838 

0.068 

0.752 

0.823 

11.44 

0.030 

0.390 

0.426 

n.  18 

0.179 

•925 

2.065 

14.65 

0.170 

1.827 

1.963 

14.41 

4287.566 

0.072 

0.796 

0.867 

12.05 

0.030 

0.390 

0.426 

11.  18 

0.180 

•936 

2.O76 

14.74 

0.169 

1.816 

1-952 

14-33 

4288.310 

0.070 

0.774 

0.845 

"•75 

0.029 

0.361 

0-397 

10.42 

0.180 

•935 

2.075 

14-73 

0.170 

1.826 

1.962 

14.40 

4289.525 

0.070 

0-774 

0.845 

"•75 

0.029 

0.361 

0-397 

10.42 

0.180 

•934 

2.074 

14.72 

0.171 

1.838 

1-974 

14.48 

4290.377 

0.072 

0-794 

0.865 

12.03 

0.030 

0.386 

0.422 

11.07 

0.179 

.922 

2.062 

I4.63 

0.172 

1.847 

1.983 

14-55 

4290.542 

0.072 

0-794 

0.865 

12.03 

0.029 

0.360 

0.396 

10.39 

o.i  80 

•932 

2.072 

14.71 

0.172 

1.846 

1.982 

14-54 

4291.630 

0.070 

0-773 

0.844 

11.74 

0.028 

0-349 

0.385 

IO.IO 

0.182 

•953 

2.093 

14.87 

0.171 

1.836 

1.972 

14.47 

*  Measured  by  L.  on  T. 
The  results  for  Plate  w  l°5i  are  continued  on  page  70. 


RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1908. 


69 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 

Plate  w  105.,.     1908,  March  10,  7h  o'n  G.  M.  T.     Measured  by  A.  on  G.  and  L.  on  T. ;   upper  half  of  table  by  A.,  lower  by  L. 

Distance  from  Limb  1.8  mm.     Quality,  good. 


P-P 


seer/ 


0     349.8 

-0.4 

o-n   275.3 

59-6 

59-9 

3°-  1 

8.4 

I.  Oil 

p       23.9 

74.6 

74.8 

15-2 

7-5 

i.ooq 

D        -7.2 

89.6 

90.4 

-0.4 

7-2 

1.  008 

Diameter  171.6  mm 

Factor        1.021 

\ 

0  =  —  o°4 

0  =  —  o°4 

0   =   IS!2 

<t>   =  }O°I 

A 

A 

j) 

»  +  vl 

£ 

A 

I) 

»  -f  Dj 

£ 

A 

p 

»  +  Dj 

£ 

A 

tl 

»  +  », 

I 

4196.699 

0.168 

km 

1.868 

km 
2.008 

14.28 

0.172 

km 
I-9I3 

km 

2-053 

14-58 

0.164 

km 
1.815 

km 
I-95I 

M-35 

0-138 

km 
1-530 

km 
I-653 

o 

13-56 

4197-25? 

0.172 

1-913 

2-053 

14-5* 

0.172     1.903 

2.043 

14-51 

0.166 

1.836 

1-972 

I4-5I 

0.136 

I.5I9 

1.642 

13-47 

4203.730 

0.172     1.898 

2.038 

14.48 

0.178 

1.963 

2.103 

14.94 

o.i  68 

1.854 

1.990 

14.  (>{ 

0.138 

1.526 

1.649 

13-53 

4207.566 

0.176 

1-95' 

2.091 

14.86 

0.172 

1.907 

2.047 

14-54 

o.i  66 

1.820 

1.956 

14-39 

0.132 

1-459 

1.582 

12.99 

4216.136 

0.170 

1.868 

2.008 

14.28 

0.172 

1.902 

2.042 

14.50 

0.162 

1.782 

1.918 

14.10 

0.136 

1.498 

1.621 

13-30 

4220.509 

0.174 

1.911 

2.051 

14-56 

0.176 

0-944 

2.084 

H-79 

o.i  68 

1.834 

1.970 

14.49 

0.140 

i-54i 

1.664 

13-67 

4232.887 

0.176 

1.936 

2.076 

14.76 

0.176 

1.924 

2.064 

14-51 

0.168 

1-837 

1-973 

14-51 

0.142 

1-456 

1-579 

12-97 

4233-328 

0.172 

1.881 

2.021 

14-37 

0.176 

1.914 

2.054 

H-59 

0.168 

1.816 

1-952 

14.36 

0.140 

1-545 

1.668 

13-70 

4257-815 

o.iSo 

1-945 

2.085 

14.82 

0.176 

1.923 

2.063 

14.65 

0.166 

1.805 

1.941 

14.27 

0.142 

1.546 

1.669 

I3-7I 

4258.477 

o.iSoj    1.945 

2-085 

14.82 

0.176 

1-945 

2-085 

14.82 

0.172 

1.858 

1.994 

14.67 

0.146!    1.590 

I-7I3 

14-05 

4265.418 

0.176;    1.918 

2.058 

14.61 

0.180 

1.908 

2.048 

14-54 

o.i  68 

1.822 

1-958 

14.40 

0.144 

1-565 

1.688 

13-85 

4266.081 

o.iSoj    1.940 

2.080 

14.78 

0.176 

1.940 

2.080 

14.78 

0.168 

1.822 

1.958 

14.40 

0.148 

1-597 

1.720 

14.11 

4268.915 

0.182 

1-973 

2-II3 

15.00 

0.180 

1.971 

2.  Ill 

14.99 

0.166 

1.799 

1-935 

14-23 

0.144 

1-574 

1.697 

13-93 

4276.836 

O.I  80 

1.956 

2.096 

14.89 

0.182 

1-935 

2.075 

14-75 

0.170 

1-837 

1-973 

14-51 

0.144 

1.561 

1.684 

13.82 

4283.169 

O.I  80 

i-95i 

2.091 

14.86 

0.180 

1.941 

2.081 

H-79 

o.i  68 

1.802 

1.938 

14.25 

0.144 

1-558 

1.681 

13-80 

4284.838 

0.182 

1.963 

2.103 

14.94 

0.180 

1.941 

2.081 

14.79 

o.i  60 

1-737 

1-873 

13-79 

0.144 

1-568 

1.691 

13-88 

4287.566 

0.180 

1.950 

2.090 

14.85 

0.180 

1.929 

2.069 

14.71 

o.i  68 

1.822 

1.958 

14.40 

0.148 

1.598 

1.721 

14.12 

4288.310 

0.180 

1.928 

2.068 

14.72 

0.180 

1.938 

2.078 

14-77 

0.168 

1.811 

1.947 

14-32 

0.144 

I-556 

1.679 

I3-78 

4289.525 

0.184 

1.971 

2.  Ill 

14.99 

0.180 

1.948 

2.088 

14-83 

0.172 

1.842 

1.978 

14-55 

0.148 

1.598 

1.721 

14.12 

4290.377 

0.180 

1.949 

2.089 

14.84 

0.176 

1.884 

2.024 

14-39 

0.168 

1-799 

1-935 

14-23 

0-144 

1-543 

1.666 

13-70 

4290.542 

0.178 

1.916 

2.056 

14.60 

0.182 

1.958 

2.098 

14.90 

0.170 

1.831 

1.967 

14.47 

0.150 

1.630 

1-753 

14-39 

4291.630 

0.192 

1.970 

2.  no 

14.98 

0.180 

1-937 

2.077 

14-77 

o.i  68 

1.820 

1.956 

14-39 

0.148 

1-597 

1.720 

14.11 

0  =  —  o?4 

0  =  —  o°4 

0  =  IS?2 

<t>  =  3o!i 

4196.699 

0-173 

1.009 

2.049 

14-55 

0.170 

1.876 

2.016 

14-32 

0.165 

1.821 

1-957 

14-39 

0.138 

1.526 

1.649 

13-53 

4197-257 

0.176 

1.942 

2.082 

14.78 

0.172 

1.897 

2.037 

14-47 

0.166 

1.831 

1.967 

14.46 

0.140 

1-547 

1.670 

I3-72 

4203.730 

0-175 

1.926 

2.066 

14.68 

0-175 

1.926 

2.066 

14.68 

0.167 

1.825 

1.961 

14.42 

0.141 

i-55i 

1.674 

I3-76 

4207.566 

0.176 

1-935 

2-075 

14-74 

0.177 

1-945 

2.085 

14.80 

o.i  66 

1.821 

J-957 

14-39 

0.141 

i-SSo 

1-673 

13-75 

4216.136 

0.174 

1.908 

2.048 

14-54 

0.176 

1.930 

2.070 

14.70 

0.165 

i.8n 

1.947 

14-32 

0.138 

i-5i7 

1.640 

13-44 

4220.509 

0.178 

1-945 

2.085 

14.80 

0.177 

1.938 

2.078 

14.76 

0.168 

1-835 

1.971 

14.49 

0.141 

1.548 

1.671 

13-73 

4232.887 

0-179 

1-952 

2.092 

14.86 

0.178 

1.942 

2.082 

14.78 

0.168 

1-833 

1.969 

14.48 

0.143 

1.564 

1.687 

I3-87 

4233-328 

0.178 

1.942 

2.082 

14.78 

0.176 

1.919 

2.059 

14.63 

o.i  68 

1-833 

1.969 

14.48 

0.140 

1-530 

1-653 

I3-56 

4257-815 

0.180 

i-95i 

2.091 

14.84 

0.180 

I-95I 

2.091 

14.84 

o.i  68 

1.821 

1-957 

H-39 

0.141 

1-532 

1-655 

13-58 

4258.47? 

0.181 

1.961 

2.IOI 

14.92 

0.180 

1.950 

2.090 

14.83 

0.169 

1.832 

1.968 

14-47 

0-143 

1-547 

1.670 

I3-72 

4265.418 

0.179 

1-935 

2-075 

14-74 

0.179 

J-935 

2.075 

14.74 

0.170 

1-833 

1.969 

14.48 

0.143 

1-547 

1.670 

I3-72 

4266.081 

0.180 

1.938 

2.078 

14.76 

0.178 

1.924 

2.064 

14.66 

o.i  68 

1.817 

1-953 

14-36 

0.143 

1-547 

1.670 

I3-72 

4268.915 

0.180 

1-937 

2.077 

14-75 

0.180 

1-943 

2.083 

14.78 

0.170 

1.831 

1.967 

14.46 

0-143 

1-545 

1.668 

I3-70 

4276.836 

0.180 

t-937 

2.077 

14-75 

0.179 

1.929 

2.069 

14.70 

0.170 

1.830 

1.966 

14-45 

0.143 

1-545 

1.668 

I3-70 

4283.169 

0.180 

1-935 

2-075 

H-74 

0.180 

1-935 

2.075 

14.74 

0.170 

1.830 

1.966 

14-45 

0.142 

I-53I 

1.654 

13-57 

4284.838 

0.180 

1-935 

2.075 

14.74 

0.180 

1-935 

2.075 

14-74 

0.170 

1.829 

1.965 

14-45 

0.142 

I-53I 

1.654 

'3-57 

4287.566 

0.182 

1-957 

2.097 

14.89 

0.180 

1-934 

2.074 

14-73 

0.172 

1.850 

1.986 

14.60 

0.144 

'•554 

1.677 

13-79 

4288.310 

0.182 

1.956 

2.096 

14.88 

0.181 

1-943 

2.083 

14.78 

0.170 

1.829 

1.965 

14-45 

0.143 

1.540 

1.663 

I3-65 

4289.525 

0.181 

1-945 

2.085 

14.80 

0.181 

1-944 

2.084 

14-79 

0.171 

1-837 

1-973 

14-51 

0.144 

1-554 

1.677 

'3-79 

4290.377 

0.180 

1-935 

2.075 

14.74 

0.180 

I-93I 

2.071 

14.72 

0.170 

1.827 

1.963 

14-43 

0.144 

1-552 

I-67S 

13-77 

4290.542 

0.182 

1-955 

2.095 

14.89 

0.182 

1-955 

2.095 

14.89 

0.172 

1.848 

1.984 

14-59 

0.145 

1.561 

1.684 

13.84 

4291.630 

0.182 

1.954     2.094 

14.88 

0.182 

1-954 

2.094 

14.88 

0.172 

1.847 

1.983 

I4-58 

0.148 

1-594 

1.717 

I4-I3 

70      AN  INVESTIGATION   OF   THE  ROTATION   PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC  METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  — Continued. 
Plate  105,  —  Continued.    Measured  by  L.  on  T. 


0  = 

2g?4 

<t>  = 

44?2 

0  = 

S9°3 

0  - 

74?3 

A 

r 

»  +  »; 

£ 

A 

V 

P  +  tlj 

£ 

A 

V 

v  +  r, 

1 

A 

» 

»  +  !>! 

£ 

km 

km 

0 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.139 

1-535 

1-658 

13-51 

0.108 

I.2OI 

1.302 

12.89 

0.066 

0.746 

0.817 

11.36 

0.028 

0-347 

0-383 

10.05 

4197-257 

0.138 

1-524 

1.647 

13-43 

0.108 

I.2OI 

1.302 

12.89 

0.068 

0.767 

0.838 

11.65 

0.028 

0-347 

0.383 

10.05 

4203.730 

0.139 

1-534 

I-657 

13-50 

O.IIO 

.219 

1.320 

13-07 

0.067 

0-754 

0.825 

11.47 

0.026 

0-337 

0-373 

9-79 

4207.566 

0.141 

1-554 

1.677 

13.66 

0.113 

•253 

1-354 

13-41 

0.067 

0-754 

0.825 

11.47 

0.027 

0-347 

0-383 

10.05 

4216.136 

0.138 

1.518 

1.641 

13-37 

0.108 

.194 

1.295 

12.82 

0.068 

0.763 

0.834 

"•59 

0.027 

0-347 

0-383 

10.05 

4220.509 

0.140 

1-538 

1.661 

13-54 

0.114 

•259 

1.360 

13-47 

0.069 

0.770 

0.841 

11.68 

0.028 

0-354 

0.390 

10.23 

4232-887 

0.143 

1.564 

1.687 

13-75 

O.IIO 

.209 

1.310 

12.97 

0.068 

0-759 

0.830 

ii-54 

0.028 

0-353 

0.389 

10.21 

4233-328 

0.142 

1-552 

1-675 

13-65 

0.113 

.242 

1-343 

13-30 

0.067 

0.748 

0.819 

"•39 

0.029 

0-363 

0-399 

10.47 

4257-815 

0.143 

1-554 

1.677 

13-66 

0.113 

•235 

I-336 

13.23 

0.070 

0.772 

0.843 

11.71 

0.030 

0-375 

0.411 

10.78 

42.58-477 

0.140 

1.522 

1.645 

13.40 

0.114 

.244 

1-345 

13-32 

0.070 

0.772 

0.843 

11.71 

0.031 

0.390 

0.426 

II.I8 

4265.418 

0.142 

1-538 

1.661 

13-53 

0.115 

•253 

1-354 

13-41 

0.070 

0.771 

0.842 

11.70 

0.028 

0-365 

0.401 

IO.52 

4266.081 

0.142 

1-537 

i.  660 

13-52 

0.117 

•274 

1-375 

13.62 

0.068 

0.752 

0.823 

11.44 

0.030 

0.378 

0.414 

10.86 

4268.915 

0.142 

i  -S36 

•659 

13-51 

O.I  I  2 

.218 

I-3I9 

13.06 

0.070 

0.770 

0.841 

11.68 

0.028 

0.364 

0.400 

10.49 

4276.836 

0.142 

1-535 

.658 

13-50 

O.II2 

.217 

1-3'S 

13-05 

0.070 

0.770 

0.841 

11.68 

0.029 

0.376 

0.412 

10.81 

4283.169 

0.144 

1-553 

.676 

13.66 

O.II7 

.268 

1.369 

13-56 

0.070 

0.770 

0.841 

11.68 

0.029 

0.376 

0.412 

10.81 

4284.838 

0.141 

1.522 

•645 

13.40 

0.116 

.260 

1.361 

13-48 

0.072 

0-793 

0.864 

12.02 

0.029 

0.376 

0.412 

10.81 

4287.566 

0.142 

i-53i 

•654 

13-48 

0.116 

2-59 

1.360 

13-47 

0.072 

0-793 

0.864 

I  2.  02 

0.028 

0-363 

0-399 

10.47 

4288.310 

0.143 

1-542 

-665 

13-56 

0.115 

•247 

1.348 

13-35 

0.070 

0.770 

0.841 

11.68 

0.028 

0.363 

0-399 

10.47 

4289.525 

0.143 

1-542 

-665 

13-56 

0.117 

.266 

1.367 

13-54 

0.071 

0.780 

0.851 

11.83 

0.028 

0-363 

0-399 

10.47 

4290.377 

0.142 

1-53° 

1-653 

13-47 

0.116 

.256 

1-357 

13-44 

0.070 

0.769 

0.840 

11.67 

0.028 

0-363 

0-399 

10.47 

4290.542 

0.143 

1.540 

1.663 

13-54 

0.114 

•234 

1-335 

13.22 

0.073 

0.801 

0.872 

12.13 

0.030 

0.388 

0.424 

II.  12 

4291.630 

0.145 

1.561 

1.684 

13.72 

0.118 

.286 

1-387 

13-74 

0.071 

0-779 

0.850 

11.82 

0.030 

0.387 

0.423 

II.  IO 

Plate  w  106.     1908,  March  10,  7h  50""  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.8  mm.     Quality,  good. 


P-F 


sec'n 


O       349.9 

-0.4 

o-n   275.4 

13-1 

14.9 

75-i 

29-3 

1.147 

P       23.9 

28.7 

29.6 

60.4 

14-7 

1.034 

D        -7.2 

44-4 

44-9 

45-i 

10.3 

1.016 

Diameter  171.6  mm 

59-6 

59-9 

30.1 

8.4 

I.  Oil 

Factor         1.021 

74-6 

74-8 

15-2 

7-5 

1.009 

^ 

<t>  = 

I5°2 

0  = 

3°°  i 

<t>  = 

t5°i* 

0  = 

6o?4* 

A 

V 

V+  »; 

£ 

A 

V 

f  +  !>i 

£ 

A 

V 

»  +  flj 

£ 

A 

V 

11  +  »! 

t 

s 

km 

km 

0 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.166 

1.833 

1.969 

14.49 

0.137 

'•SIS 

1-638 

13-44 

O.I  I  2 

1.248 

1-347 

13-55 

0.064 

0-737 

0.806 

11.58 

4I97-257 

0.166 

1.832 

1.968 

14.48 

0.139 

•533 

•656 

13-59 

0.108 

1.204 

I-303 

13.11 

0.064 

0.727 

0.796 

11-45 

4203.730 

0.169 

1.  860 

1.996 

14.67 

0.140 

•544 

.667 

13.68 

O.II2 

1.256 

•355 

13-63 

0.066 

0.747 

0.816 

11.72 

4207.566 

o.i  68 

1.848 

1.984 

14.60 

0.140 

•543 

.666 

13-67 

0.104 

I-I55 

•254 

13.62 

0.064 

0-713 

0.782 

11.23 

4216.136 

0.166 

1.822 

1.958 

14.41 

0.138 

•517 

.640 

13.46 

0.108 

.186 

-285 

12.93 

0.068 

0-755 

0.824 

11.84 

4220.509 

o.i  68 

1-837 

1-973 

14.52 

0.141 

•548 

.671 

13-71 

O.II2 

•239 

-338 

13.46 

0.068 

0-754 

0.823 

11.83 

4232.887 

o.i  68 

1.835 

1.971 

14.50 

0.141 

•541 

1.664 

13.65 

0.106 

.168 

.267 

12.75 

0.064 

0.707 

0.776 

11.14 

4233-328 

0.168 

1-834 

1.970 

14.49 

0.140 

•530 

i-*53 

13-57 

O.IIO 

.212 

•3" 

13-19 

0.066 

0.740 

0.809 

11.62 

4257-815 

0.169 

1-835 

1.971 

14.50 

0.143 

•554 

1.677 

13-75 

O.II2 

-237 

-336 

13-44 

0.066 

0.725 

0.794 

11.42 

4258.477 

0.170 

1.843 

1.979 

14.56 

0.142 

•542 

1.665 

13-66 

O.IIO 

.204 

•303 

13.11 

0.064 

0.702 

0.771 

11.08 

4265.418 

0.169 

1.828 

1.964 

14.46 

0.141 

•525 

1.648 

13-52 

O.II4 

•245 

•344 

13-52 

0.066 

0-734 

0.803 

n-54 

4266.081 

0.170 

1.836 

1.972 

14.51 

0.142 

•534 

1-657 

13.60 

O.II2 

-234 

•333 

13-41 

0.066 

0-734 

0.803 

"•54 

4268.915 

0.170 

I-835 

1.971 

14.50 

0-143 

•547 

1.670 

13-70 

0.116 

-254 

•353 

13.61 

0.066 

0-733 

0.802 

"•53 

4276.836 

0.170 

1.834 

1.970 

14.49 

0.141 

.522 

1.645 

13-50 

O.IIO 

.198 

.298 

13-05 

0.066 

0.722 

0.791 

11.40 

4283.169 

0.169 

1.820 

1.956 

14.40 

0.142 

i.53i 

1.654 

13-57 

O.IIO 

1.196 

•295 

13-03 

0.066 

0-730 

0.799 

11.49 

4284.838 

0.170 

1.830 

1.966 

14.47 

0.141 

1.520 

1.643 

13.48 

0.108 

I.I74 

•273 

12.81 

0.064 

0.707 

0.776 

11.15 

4287.566 

0.172 

1.850 

1.986 

14.61 

0.143 

1-542 

1.665 

13.66 

O.II2 

1.184 

•  283 

12.91 

0.066 

0.720 

0.789 

"•34 

4288.310 

0.170 

1.830 

1.966 

14.47 

0.142 

1-533 

1-656 

13-59 

O.II2 

1.226 

1-325 

13-33 

0.066 

0.730 

0.799 

11.49 

4289.525 

0.171 

1.840 

1.976 

14-54 

0.143 

1.540 

1.663 

13.64 

O.II2 

1.205 

1.304 

13.12 

0.062 

0.685 

0-754 

10.83 

4290.37? 

0.170 

1.828 

1.964 

14-46 

0.142 

1-529 

1.652 

13-56 

O.IlS 

1.161 

1.260 

12.69 

0.064 

0.695 

0.764 

11.07 

4290.542 

0.171 

1.839 

1-975 

14-53 

0.142 

1.528 

1.651 

13-55 

0.116 

1.247 

I-346 

13-54 

0.064 

0.705 

0.774 

II.  12 

4291.630 

0.172 

1.848 

1.984 

14.60 

0.144 

i-SSO 

1-673 

13-72 

0.116 

1.247 

1.346 

13-54 

0.064 

0-705 

0.774 

II.  12 

*  Measured  by  A.  on  G. 


RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1908. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  <a  106 — Continued.     Measured  by  L.  On  T. 


\ 

*-7sV 

0  =  45!! 

0  =  6o°4 

<t>  =  7S?i 

\ 

A 

V 

,+,, 

1 

A 

V 

»  +  », 

« 

A 

V 

v  4-  vl 

« 

A 

V 

,  +  ., 

• 

4196.699 

0.030 

km 

0.377 

km 
0.411 

n-35 

0.108 

km 
1.189 

km 
1.288 

12.96 

0.058 

km 

0.656 

km 
0.725 

e 

10.65 

0.028 

km 
0.351 

km 
0-38  = 

10.63 

4197.257 

0.028 

0.366 

0.400 

11.04 

0.108 

1.189 

1.288 

12.96 

0.058 

0.656 

0.725 

10.65 

0.029 

0.361 

0-395 

10.91 

4203.730 

0.032 

0.400 

0-434 

11.98 

O.I  08 

1.196 

1-295 

13-03 

0.058 

0-655 

0.724 

10.64 

0.029 

0.361 

0-395 

10.91 

4207.566 

0.030 

0.376 

0.410 

11.32 

0.108 

I-I95 

1-295 

13.02 

0.060 

0.676 

0-745 

10.80 

0.030 

0.369 

0-403 

11.13 

4216.136 

0.030 

0-375 

0.409 

11.29 

0.109 

1.204 

I-303 

13.11 

0.058 

0-653 

0.722 

10.62 

0.030 

0.369 

0.403 

11.13 

4220.509 

0.036 

0-437 

0.471 

13.00 

0.108 

1.188 

1.287 

12.95 

0.060 

0.672 

0.741 

10.71 

0.031 

0.380 

0.414 

11.44 

4232.887 

0.032 

0.414 

0.448      12.37 

0.108 

1.187 

1.286 

12.94 

0.061 

0.682 

0.751 

10.85 

0.030 

0.368 

0.402 

II.  IO 

4233-328 

0.028 

0-335 

0.369 

10.19 

0.109 

1.197 

1.296 

13.04 

0.060 

0.671 

0.741 

10.71 

0.030 

0.368 

0.402 

II.  10 

4257-815 

0.032 

0.392 

0.426 

11.76 

O.IIO       1.200 

1.299 

13-07 

0.062 

0.687 

0.756 

10.91 

0.030     0.366 

0.400 

11.05 

4258.477 

0.032 

0.392 

0.426 

11.76 

O.IIO 

i.  200 

1.299 

13-07 

0.062 

0.687 

0.756 

10.91 

0.030     0.366 

0.400 

11.05 

4265.418 

0.028 

0.360 

0-394 

10.88 

0.108 

1.176 

1-275 

12.83 

0.062 

0.687 

0.756 

10.91 

0.031 

0.376 

0.410 

11-33 

4266.081 

0.032 

0-393 

0.427 

11.79 

O.II2 

1.219 

1.318 

13.26 

0.061 

0.677 

0.746 

10.78 

0.032 

0.386 

0.420 

1  1.  60 

4268.915    1  0.030 

0.370 

0.404 

11.15 

0.109 

1-185 

1.284 

12.92 

0.062 

0.686 

o-755 

10.90 

0.032!    0.386 

0.420 

1  1.  60 

4276.836 

0.032 

0.380 

0.414 

"•43 

O.IO8       I.I74 

1-273 

12.81 

0.062 

0.686 

0-755 

10.90 

0.031 

0-375 

0.400 

11.30 

4283.169 

0.032 

0-379 

0.413 

11.40 

O.IIO:      I.2O2 

1.301 

13.09 

0.062 

0.686 

0-755 

10.90 

0.031 

0-375 

0.400 

11.30 

4284.838 

0.032 

0-379 

0.413 

11.40 

O.lOg 

1.181 

1.280 

12.95 

0.063 

0.696 

0.765 

11.13 

0.032 

0.386 

0.420 

1  1.  60 

4287.566 

0.032 

0-379 

0.413 

11.40 

O.IIO 

1.193 

1.292 

13.00 

0.062 

0.685 

0-754 

10.89 

0.032 

0.386 

0.420 

n.  60 

4288.310 

0.032 

0-379 

0.413 

11.40 

O.IIO 

1.192 

1.291 

12.99 

0.062 

0.685 

0-754 

10.89 

0.032 

0.385 

0.410 

11-57 

4289.525 

0.032 

0.402 

0.436 

12.04 

O.IIO 

1.192 

1.291 

12.99 

0.063 

0.695 

0.764 

II.  12 

0.032 

0-385 

0.410 

n-57 

4290-377 

0.030 

0.368 

0.402 

II.  10 

O.IIO 

1.190 

1.289 

12.97 

0.060 

0.661 

0.730 

10.72 

0.030 

0.364 

10.99 

4290.542 

0.032 

0.368 

0.402 

II.  IO 

O.II2 

1.  212 

1.311 

13-19 

0.063 

0-693 

0.762 

II.  10 

0.032 

0.384 

0.418 

"-S5 

4291.630 

0.034 

0.389 

0.423 

11.68 

O.I  I  2 

1.  212 

1.311 

13-19 

0.062 

0.683 

0.752 

10.87 

0.030 

0.363 

0-395 

10.97 

<t>  =  45!  i 

0  =  6o°4 

*-** 

, 

A 

V 

.  +  ., 

« 

A 

V 

M-,, 

* 

A 

V 

.  +  ., 

• 

4196.699 

0.108 

km 

1.  201 

km 
1.300 

13 

08 

0.062 

km 
0.703 

km 
0.772 

11.09 

0.028 

km 

0.351 

km 
0.385 

10.63 

4197-257 

0.108 

1.  201 

1.300 

13 

08 

0.062 

0.703 

0.772 

11.09 

0.030 

0.376 

0.410 

II-33 

4203.730 

0.108 

I.I98 

•297 

I3-05 

0.063 

0.713 

0.782 

11.24 

0.030 

0-373 

0.407 

11.24 

4207.566 

O.IIO 

I.2I9 

.318 

13 

26 

0.063 

0.711 

0.780 

II.  21 

0.028 

0-349 

0.383 

10.58 

4216.136 

O.IIO 

I.2I5 

-3H 

13 

22 

0.064 

0.720 

0.789 

"•34 

0.028 

0-349 

0-383 

10.58 

4220.509 

0.109 

1.203 

.302 

13 

IO 

0.064 

0.719 

0.788 

11.32 

0.029 

0-359 

0-393 

10.86 

4232.887 

O.IIO 

I.2O9 

.308 

'3 

16 

0.065 

0-730 

0.799 

11.48 

0.029 

0-359 

0-393 

10.86 

4233-328 

O.IIO 

I.2O9 

-308 

13 

16 

0.067 

0.750 

0.819 

11.77 

0.030 

0.371 

0.405 

11.19 

4257-815 

O.III 

1.  212 

•3" 

13 

19 

0.066 

0-734 

0.803 

n-53 

0.032 

0-393 

0.427 

11.79 

4258.477 

O.IIO 

1.  201 

.300 

13.08 

0.066 

0-734 

0.803 

"•53 

0.031 

0.380 

0.414 

11.44 

4265.418 

O.IIO 

I.2OO 

.299 

I3-07 

0.067 

0-743 

0.812 

11.67 

0.029 

0-354 

0.388 

10.72 

4266.081 

O.IIO 

I.I99 

.298 

13 

06 

0.066 

0.732 

0.801 

11.50 

0.032 

0-392 

0.426 

11.77 

4268.915 

O.III 

I.2O7 

.306 

13 

•14 

0.066 

0-731 

0.800 

11.48 

0.030 

0.365 

0-399 

11.02 

4276.836 

O.III 

I.2O4 

•303 

13.11 

0.066 

0.730 

0.799 

11.47 

0.032 

0.392 

0.426 

11.77 

4283.169 

O.IIO 

I-I93 

.292 

13 

.00 

0.067 

0.740 

0.809 

11.63 

0.031 

0-379 

0.413 

11.41 

4284.838 

O.IIO 

I.I94 

•293 

13 

.01 

0.066 

0.729 

0.798 

11.46 

0.032 

0.391 

0.425 

11-74 

4287.566 

O.IIO 

I.I94 

•293 

13 

01 

0.066 

0.729 

0.798 

11.46 

0.032 

0.391 

0.425 

11.74 

4288.310 

O.II2 

1.203 

.302 

13 

.10 

0.067 

0.738 

0.807 

1  1.  60 

0.032 

0.391 

0.425 

11.74 

4289.525 

O.III 

1.203 

1.302 

13 

.10 

0.067 

0.738 

0.807 

1  1.  60 

0.031 

0.380 

0.414 

11.44 

4290.377 

O.IIO 

I-I93 

1.292 

13.00 

0.065 

0.717 

0.786 

11.30 

0.030 

0.368 

0.402 

II.  II 

4290.542 

O.II2 

1.  212 

1.311 

I3-I9 

0.066 

0.728 

0.797 

11.44 

0.030 

0.368 

0.402 

II.  II 

4291.630 

O.III 

I.2OI 

1.300 

13-08 

0.068 

0.749 

0.818 

11.76 

0.030 

0.367 

0.401 

II.O9 

*  Measured  by  A.  on  G. 


72      AN  INVESTIGATION  OF  THE  ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC   METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  113.     1908,  April  8,  7h  45™  G.  M.  T.     Measured  by  A.  on  G.     Distance  from  Limb  1.4  mm.     Quality,  good. 


t-P 


seci) 


O          1 8.6 
O-D    304.1 
I  P          26.5 
D         -6.0 
Diameter  170.7  mm 
Factor        1.017 


0.0 

13.0 

14-3 

75-7 

25.0 

1.103 

28.7 

29-3 

60.7 

12.3 

1.024 

44-9 

45-2 

44.8 

8.6 

1.  01  1 

60.0 

60.2 

29.8 

6.9 

1.007 

7S-o 

75-i 

14.9 

6.2 

i.  006 

90.0 

90.0 

o.o 

6.0 

i.  006 

<t>  =  o°o 

,  =  ,4:9 

0  =  2Q?8 

A 

V 

V  +  fj 

1 

A 

V 

,+,, 

1 

A 

' 

,  +  ,, 

k 

4196.699 

0.176 

km 

1.919 

km 

2.056 

14.60 

0.164 

km 
1.788 

km 
L923 

14.12 

0.136 

km 

1.487 

km 
I.6n 

13-18 

4197-257 

0.180 

1-973 

2.  no 

14.99 

o.i  66 

1.820 

1-955 

14-37 

0.140 

1-529 

I-653 

13-56 

4203.730 

0.182 

1.990 

2.127 

15.11 

0.168 

1.837 

1.972 

14.48 

0.144 

1-567 

1.691 

13.84 

4207.566 

0.180 

1.967 

2.104 

14-95 

0.164 

1.804 

1-939 

14.24 

0.140 

1-532 

1.656 

13-58 

4216.136 

0.176 

1.918 

2.055 

14-59 

0.164 

1.788 

1.923 

14.12 

0.138 

1.502 

1.626 

13-30 

4220.509 

o.i  80 

1.960 

2.097 

14.89 

0.172 

1.862 

1-997 

14.68 

0.144 

1.562 

1.686 

13.81 

4232.887 

0.184 

1.984 

2.  121 

15.06 

0.172 

1.876 

2.OII 

14.78 

0.144 

1-572 

1.696 

13.88 

4233-328 

0.180 

1-951 

2.088 

14.83 

0.166 

I.8oo 

1-935 

14.21 

0.136 

1-479 

1.603 

13.12 

0.184 

1.971 

2.108 

14.98 

0.174 

1.863 

1.998 

14.68 

0.146 

1-566 

1.690 

13.84 

4258.477 

0.182 

1.960 

2.097 

14.89 

0.172 

1.842 

1.977 

14-52 

0.146 

1-583 

1.707 

13-97 

4265.418 

0.184 

1.987 

2.124 

15.09 

0.170 

1.827 

1.962 

14.41 

0.148 

1.588 

1.712 

14.01 

4266.081 

0.184 

1.977 

2.II4 

15.02 

0.172 

1.849 

1.984 

14.58 

0.146 

1-573 

1.697 

13.89 

4268.915 

0.084 

1-975 

2.  112 

15.01 

0.172 

1.857 

1.992 

14-63 

0.148 

1-587 

1.711 

14.00 

4276.836 

0.188 

2.003 

2.140 

15.22 

0.172 

1.854 

1.989 

14.61 

0.148 

1.596 

1.720 

14.07 

4283.169 

0.184 

1-977 

2.II4 

15.02 

0.176 

I.88I 

i.  202 

14.82 

0.152 

1.627 

i-75i 

14-31 

4284.838 

0.180 

1-934 

2.071 

14.71 

0.176 

1-775 

1.910 

14.03 

0.140 

1.498 

1.622 

13-27 

4287.566 

0.184 

1.966 

2.103 

14.94 

0.170 

1.816 

I-95I 

14-33 

0.144 

1.541 

1-665 

13.60 

4288.310 

0.184 

1-954 

2.091 

14.85 

0.176 

1.879 

1.  201 

14.80 

0.148 

1-572 

1.696 

13.88 

4289.525 

0.184 

1.965 

2.IO2 

H-93 

0.172 

1.848 

1.983 

14-57 

0.146 

1.562 

1.686 

13-91 

4290.377 

0.184 

1-953 

2.090 

14.84 

o.i  68 

1.794 

1.929 

14.17 

0.148 

1.582 

1.706 

13.96 

4290.542 

0.184 

1.964 

2.IOI 

14-93 

0.172 

1.836 

1.970 

14.47 

0.144 

i-5Si 

1-675 

13-72 

4291.630 

0.182 

1.942 

2.079 

14.76 

0.172 

1.847 

1.982 

14.56 

0.144 

I-S5I 

1-675 

13-72 

<t>  =  44°8 

0  =  60^7 

0  =  7S!7 

4196.699 

0.104 

J-I35 

1.239 

12-39 

0.066 

0.736 

O.SlO 

11.76 

0.028 

0-325 

0.366 

10-54 

4197-257 

0.108 

1.202 

1.306 

13.06 

0.066 

0.725 

0.799 

n.6o 

0.026 

0.314 

0-355 

IO.22 

4203.730 

0.108 

I.I76 

1.280 

12.80 

0.068 

0-745 

0.8l9 

11.89 

0.024 

0-303 

0-344 

9.92 

4207.566 

0.104 

I-I53 

1-257 

12.57 

0.066 

0.723 

0.797 

"•57 

0.024 

0.302 

0-343 

9.88 

4216.136 

0.106 

1.161 

1.265 

12.65 

0.068 

0-743 

0.817 

11.86 

0.028 

0-323 

0.364 

10.48 

4220.509 

0.108 

I-I93 

1.297 

12.97 

0.066 

0.805 

11.70 

0.028 

0.346 

0.387 

11.14 

4232.887 

0.116 

1.  210 

L3I4 

13-14 

0.064 

0.706 

0.780 

11.23 

0.028 

0.321 

0.362 

IO.42 

4233-328 

0.108 

I.lS? 

1.291 

12.91 

0.064 

0.718 

0.792 

11.50 

0.024 

0.300 

0.341 

9.82 

4257-815 

0.116 

1-245 

1-349 

13-49 

0.066 

0.724 

0.798 

"•59 

0.028 

0-343 

0.384 

1  1.  06 

4258.477 

O.I  12 

1.  212 

1.316 

13.16 

0.066 

0.724 

0.798 

"•59 

0.028 

0-332 

0-373 

10.74 

4265.418 

0.108 

1.167 

1.271 

12.71 

0.064 

0.711 

0.785 

11.40 

0.028 

0.321 

0.362 

IO.42 

4266.081 

O.II2 

1.220 

I-324 

13-24 

0.064 

0.711 

0.785 

11.40 

0.028 

0-331 

0-372 

10.72 

4268.915 

o.iio 

I.lS? 

1.291 

12.91 

0.068 

0.742 

0.816 

11.85 

0.030 

0-352 

0-393 

11.31 

4276.836 

O.II2 

1.  2O6 

1.310 

13.10 

0.070 

0.763 

0.837 

12.15 

0.028 

0.320 

0.361 

10.40 

4283.169 

0.108 

1.161 

1.265 

12.65 

0.068 

0.751 

0.825 

11.98 

0.028 

0.340 

0.381 

10.97 

4284.838 

O.IIO 

1.182 

1.286 

12.86 

0.068 

o.75i 

0.825 

11.98 

0.028 

0.330 

0-371 

10.68 

4287.566 

0.116 

1.246 

1-350 

13-50 

0.066 

0.718 

0.792 

11.50 

0.024 

0.286 

0-327 

9.42 

4288.310 

O.IIO 

1.182 

1.286 

12.86 

0.068 

0.728 

0.802 

11.65 

0.026 

0.307 

0.348 

10.02 

4289.525 

0.116 

1-245 

1-349 

13-49 

0.066 

0.706 

0.780 

11.23 

0.028 

0.317 

0-358 

IO.3I 

4290.377 

O.II2 

i.  202 

1.306 

13.06 

0.064 

0.706 

0.780 

11.23 

0.026 

0.296 

0-337 

9.71 

4290.542 

O.II2 

1.  212 

1.316 

13.16 

0.066 

0.716 

0.790 

II-37 

0.026 

0.307 

0.348 

10.02 

4291.630 

O.II2 

I.I90 

1.294 

12.94 

0.068 

0.728 

0.802 

11.65 

0.024 

0.296 

0-337 

9.71 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1908. 


73 


TABLE  n.  —  RESULTS  TOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1908  —  Continued. 
Plate  w  113  —  Continued.     Measured  by  L.  on  T. 


*- 

o°o 

*- 

I4°9 

*- 

2Q°8 

A 

tl 

•  •Mi 

« 

A 

V 

M-i 

« 

A 

' 

V  +  V  l 

« 

km 

km 

i 

km 

km 

0 

km 

km 

0 

4196.699 

0.175 

1-934 

2.071 

14.70 

0.162 

.784 

1.919 

14.10 

0.140 

1-533 

I-657 

13-55 

4197.257 

0.177 

1-935 

2.072 

14.71 

o.i  66 

.815 

1-950 

14-33 

0.142 

I-556 

1.  680 

13.74 

4203.730 

0.182 

,  1-984 

2.  121 

15.06 

o.i  68 

•834 

1.969 

14.47 

0.144 

1-574 

1.698 

13.89 

4207.566 

0.179 

.961 

2.098 

14.89 

o.i  66 

.810 

1-945 

14.29 

0.144 

•572 

1.696 

13.59 

4216.136 

0-177 

.924 

2.061 

14-63 

o.i  68 

.827 

1.962 

14.41 

0.145 

.580 

1.704 

13.94 

4220.509 

0.179 

•943 

2.080 

14-77 

0.169 

•835 

•970 

14.47 

0-145 

•577 

1.701 

13.92 

4232.887 

0.180 

•947 

2.084 

14.79 

0.172 

.847 

.982 

14.56 

0.145 

•571 

1.695 

13.87 

4233-328 

0.180 

•945 

2.082 

14.78 

o.i  68 

.817 

•952 

14-34 

0.145 

•570 

1.694 

13.86 

4257-815 

0.181 

•953 

2.090 

14.84 

0.169 

-825 

.960 

14.40 

0.146 

1-574 

1.698 

13.89 

4258.477 

0.181 

•945 

2.082 

14.78 

0.171 

.840 

•975 

14-5  I 

0.146 

I-57I 

1.695 

13.87 

4265.418 

0.181 

•939 

2.076 

14-73 

0.171 

-8.34 

.969 

14.47 

0.144 

1.546 

1.670 

13.66 

4266.081 

0.180 

•939 

2.076 

14-73 

0.170 

-825 

.960 

14.40 

0-145 

I-556 

1.680 

13-74 

4268.915 

0.180 

•937 

2.074 

14.72 

0.172 

.846 

.981 

14-55 

0.146 

1.566 

1.690 

13.83 

4276.836 

0.181 

•925 

2.062 

14.64 

0.171 

.827 

.962 

14.41 

0-145 

1-553 

1.677 

13.72 

4283.169 

0.181 

•938 

2-075 

14-73 

o.i73 

.848 

•983 

14-57 

0.144 

1-539 

1.663 

13.61 

4284.838 

0.183 

.948 

2.085 

14.80 

o.i  68 

.792 

1.927 

14.16 

0.144 

1-537 

1.661 

13-59 

4287.566 

0.182 

•940 

2.077 

14.74 

0.171 

-823 

1.9158 

14-38 

0.146 

I-558 

1.682 

13.76 

4288.310 

0.182 

.938 

2-075 

14-73 

0.173 

•843 

1.978 

14-53 

0.145 

1.548 

1.672 

13.68 

4289.525 

0.184 

•958 

2.095 

14.87 

0.169 

.801 

1.936 

14.22 

0.144 

1-537 

1.  66  1 

13.59 

4290.377 

0.183 

1.947 

2.084 

14.79 

0.169 

.801 

1.936 

14.22 

0.147 

1-567 

1.691 

13.83 

4290.542 

0.182 

1-937 

2.074 

14.72 

o.i75 

.860 

1-995 

14.66 

0.148 

1-578 

1.702 

13.92 

4291.630 

0.183 

1.948 

2.085 

14.80 

0.173 

.842 

1.977 

14.52 

0.142 

LSI4 

1.638 

13.40 

*- 

44^8 

*- 

60!? 

#- 

7S!7 

4196.699 

0.106 

1.165 

.269 

12.69 

0.064 

0.712 

0.786 

11.42 

0.024 

0.288 

0.329 

9-47 

4197-257 

0.109 

1.198 

.302 

13.02 

0.063 

0.701 

0-775 

11.25 

0.026 

0.309 

0.350 

10.07 

4203.730 

O.IIO 

1.206 

.310 

13.10 

0.065 

0.721 

o-795 

11-55 

0.027 

0.319 

0.360 

10.36 

4207.566 

0.109 

I-I95 

•299 

12.99 

0.066 

o-73i 

0.805 

11.69 

0.026 

0.307 

0.348 

IO.OI 

4216.136 

o.i  06 

I-I59 

.263 

12.63 

0.064 

0.708 

0.782 

11.36 

0.027 

0.318 

0-359 

10.33 

4220.509 

0.108 

1.179 

.283 

12.83 

0.065 

0.717 

0.791 

n-49 

0.026 

0.307 

0.348 

IO.OI 

4232.887 

O.IIO 

1.196 

.300 

13.00 

0.066 

0-725 

0.799 

1  1.  60 

0.028 

0-332 

0-373 

10.74 

4233-328 

o.i  06 

I-I53 

1-257 

12.57 

0.067 

o.737 

0.811 

11.78 

0.028 

0-332 

0-373 

10.74 

4257-815 

O.I  II 

i.  200 

1.304 

13-04 

0.067 

0.732 

0.806 

11.70 

0.028 

0.330 

0-371 

10.68 

4258.477 

O.I  II 

1.199 

I.303 

13-03 

0.066 

0.721 

0-795 

"•55 

0.028 

0-330 

0-371 

10.68 

4265.418 

O.IIO 

1.188 

1.292 

12.92 

0.065 

0.710 

0.784 

"•39 

0.026 

0.308 

0-349 

10.04 

4266.081 

0.113 

1.217 

1.321 

13.21 

0.065 

0.709 

0.783 

11.38 

0.026 

0.308 

0-349 

10.04 

4268.915 

O.II2 

1.206 

1.310 

13.10 

0.067 

0.730 

0.804 

11.66 

0.029 

0-339 

0-379 

10.91 

4276.836 

O.I  12 

1.204 

1.308 

13.08 

0.066 

0.718 

0.792 

11.50 

0.028 

0.328 

0.369 

10.62 

4283.169 

O.IIO 

1-183 

1.287 

12.87 

0.066 

0.717 

0.791 

"•49 

0.028 

0.328 

0.369 

10.62 

4284.838 

O.IIO 

1.182 

1.286 

12.86 

0.066 

0.716 

0.790 

11.48 

0.029 

0-339 

0.380 

10.93 

4287.566 

O.IIO 

1.180 

1.284 

12.84 

0.067 

0.727 

0.801 

11.63 

0.028 

0.328 

0.369 

10.62 

4288.310 

O.IIO 

1.179 

1.283 

12.83 

0.066 

0.717 

0.791 

11.49 

0.029 

0.338 

0-379 

10.91 

4289.525 

O.I  I  2 

i.  200 

I-304 

13.04 

0.066 

0.716 

0.790 

11.48 

0.028 

0.328 

0.369 

10.62 

4290.37? 

O.III 

o.i  88 

1.292 

12.92 

0.061; 

0.705 

0.779 

11.32 

0.026 

0.307 

0.348 

IO.OI 

4290.542 

O.II2 

1.199 

I-303 

13-03 

0.068 

0-735 

0.809 

n-74 

0.028 

0.328 

0.369 

10.62 

4291.630 

O.II2 

1.199 

13-03 

0.066 

0.716 

0.790 

11.48 

0.029 

0.338 

0-379 

10.91 

74      AN   INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  a  ii7r     1908,  May  26,  I2h  om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.6  mm.     Quality,  good. 


*-* 

7T 

0 

•n 

sec)) 

o°6 

° 

0 

0         6S-3 

14.1 

I4.I 

75-9 

4-7 

1.003 

O-O    350.1 

29.6 

29.6 

60.4 

2-3 

I.OOI 

P          17-4 

45-4 

45-4 

44.6 

1.6 

i.ooo 

D        -1.8 

60.6 

60.6 

29.4 

1.4 

I.OOO 

Diameter  168.7  mm 

75-6 

75-6 

14.4 

1.2 

I.OOO 

Factor        1.019 

90.6 

0.6 

-0.6 

I.I 

I.OOO 

0  = 

-ot« 

0  = 

M.% 

0  = 

2Q  4 

, 

A 

» 

,  +  „ 

* 

A 

V 

.  +  „ 

' 

A 

V 

1)  -\-  1) 

t 
S 

4196.699 

0.173 

km 

1.887 

km 
2.021 

14-35 

0-159 

km 
1-735 

km 
1.868 

13.69 

0.138 

km 
I.507 

km 
1.632 

1.3-30 

4197-257 

0.172 

1.877 

2.0II 

14.28 

o.i  60 

1-745 

1.878 

13-77 

0.138 

1.506 

1.631 

I3-30 

4203.730 

0.176 

I-9I5 

2.049 

14-55 

0.163 

1.762 

1.895 

13.89 

0.142 

1-545 

1.670 

13-61 

4207.566 

0.177 

1.924 

2.058 

14.61 

0.161 

1-747 

i.  880 

13-78 

0.142 

•544 

1.669 

13.61 

4216.136 

0.175 

1.898 

2.032 

14-43 

0.161 

1-745 

1.878 

13-77 

0.139 

.508 

1-633 

I3-3I 

4220.509 

0.178 

1.928 

2.062 

14.64 

0.163 

1.764 

1.897 

13-91 

0.140 

•Si? 

1.642 

I3-38 

4232.887 

0.179 

1.930 

2.064 

14.66 

0.164 

1.768 

1.901 

13-94 

0.143 

•543 

1.668 

13.60 

4233-328 

0.178 

1.920 

2.054 

14.58 

0.164 

1.767 

1.900 

13-93 

0.141 

•522 

1.647 

13-43 

4257-815 

0.182 

I-95I 

2.085 

14.80 

0.168 

1.797 

1.930 

14-15 

0.145 

•554 

1-6-79 

13.69 

4258.477 

0.179 

1.918 

2.052 

14-57 

0.165 

1.766 

1.899 

13.92 

0.144 

•544 

1.669 

13.61 

4265.418 

o.i  80 

1.924 

2.058 

14.61 

o.i  66 

.767 

1.900 

13-93 

0.143 

•528 

1-653 

13-47 

4266.081 

0.181 

1-934 

2.068 

14.68 

0.166 

.776 

1.909 

13-99 

0.146 

.560 

1.685 

13-74 

4268.915 

0.180 

1.920 

2.054 

14.58 

0.166 

.765 

1.898 

13-91 

0.146 

•559 

1.684 

13-73 

4276.836 

0.182 

1.941 

2.075 

14-73 

0.166 

.765 

1.898 

13-91 

0.143 

•523 

1.648 

13-43 

4283.169 

0.178 

1.896 

2.030 

14.41 

0.167 

•775 

1.908 

13-99 

0.144 

•532 

1-657 

13-Si 

4284.838 

0.181 

1.924 

2.058 

14.61 

0.166 

.767 

1.900 

13-93 

0.145 

•542 

1.667 

13-59 

4287.566 

0.181 

1.923 

2.057 

14.61 

0.165 

•743 

1.876 

13-75 

0.144 

•531 

1.656 

13-50 

4288.310 

0.182 

1-934 

2.068 

14.68 

0.165 

•755 

1.888 

13.84 

0.146 

•552 

1.677 

13-67 

4289.525 

0.182 

1-933 

2.067 

14.68 

0.165 

•755 

1.888 

13.84 

0.146 

•551 

1.676 

13-66 

4290.377 

0.182 

1-933 

2.067 

14.68 

0.165 

•754 

1.887 

13-83 

0.146 

•550 

1-675 

13-65 

4290.542 

0.182 

1.932 

2.066 

14.67 

0.167 

•774 

1.907 

13.98 

0.147 

.561 

1.686 

13-74 

4291.630 

0.184 

1-954 

2.088 

14-83 

0.166 

0.764 

1.897 

13.90 

0.148 

•570 

1.695 

13.82 

0  = 

44?6 

0  = 

ao!4 

0  = 

,* 

4196.699 

0.108 

1.178 

1.285 

12.82 

0.068 

0.741 

0.822 

11.82 

0.029 

0.307 

0-355 

10-35 

4197-257 

O.I  08 

1.178 

1.285 

12.82 

0.067 

0.731 

0.812 

11.68 

0.028 

0.307 

0-355 

10-35 

4203.730 

0.108 

I-I73 

1.280 

12.77 

0.069 

0.751 

0.832 

11.96 

0.030 

0.329 

0-377 

10.99 

4207.566 

O.IIO 

1.194 

1.301 

12.98 

0.073 

0-793 

0.874 

12.57 

0.029 

0.318 

0.366 

10.67 

4216.136 

0.108 

1.171 

1.278 

12-75 

0.068 

0.738 

0.819 

11.78 

0.029 

0.317 

0-365 

10.64 

4220.509 

O.IIO 

1.190 

1.297 

12.94 

0.070 

0.758 

0.839 

12.07 

0.030 

0.327 

0-375 

10.93 

4232.887 

O.IIO 

1.186 

1.293 

12.90 

0.070 

0-754 

0.835 

12.01 

0.030 

0-325 

0-373 

10.87 

4233-328 

O.II2 

1.208 

I-3'S 

13.12 

0.069 

0-744 

0.825 

11.86 

0.029 

0.314 

0.362 

10.55 

4257-815 

O.II2 

1.  201 

1.308 

I3-04 

0.072 

0.771 

0.852 

12.25 

0.030 

0.322 

0.370 

10.79 

4258.477 

O.II4 

1.  221 

1.328 

I3-25 

0.070 

0.751 

0.832 

11.96 

0.032 

0.346 

0-394 

11.49 

4265.418 

O.I  1  1 

I.I88 

1-295 

12.92 

0.071 

0.758 

0.839 

12.07 

0.031 

0-334 

0.382 

11.14 

4266.081 

0.  112 

I.I97 

1.304 

13.01 

0.071 

0.758 

0.839 

12.07 

0.032 

0-344 

0.392 

"•43 

4268.915 

O.II3 

1.  206 

I.3I3 

13.10 

0.070 

0.747 

0.828 

11.91 

0.030 

0.322 

0.370 

10.79 

4276.836 

O.I  1  1 

I.I83 

1.290 

12.87 

0.072 

0.768 

0.849 

12.21 

0.030 

0.321 

0.369 

10.76 

4283.169 

O.II2 

I.igi 

1.298 

12-95 

0.070 

0-745 

0.826 

11.88 

0.029 

0.310 

0.358 

10.44 

4284.838 

O.III 

I.lSo 

1.287 

12.84 

0.070 

0-745 

0.826 

11.88 

0.032 

0-341 

0.389 

n-34 

4287.566 

O.II4 

1.  212 

1.319 

13.16 

0.071 

0-755 

0.836 

I2.O2 

0.030 

0.321 

0.369 

10.76 

4288.310 

O.II3 

I.2OI 

1.308 

13.04 

0.072 

0.765 

0.846 

12.17 

0.032 

0.341 

0.389 

II-34 

4289.525 

O.II2 

I.I9I 

1.298 

12-95 

0.071 

0-755 

0.836 

I2.O2 

0.030 

0.320 

0.368 

10.73 

4290.377 

O.I  1  2 

I.I90 

1.297 

12.94 

0.073 

0.776 

0.857 

12.32 

0.030 

0.320 

0.368 

10-73 

4290.542 

O.II4 

1.  211 

1-318 

I3-I5 

0.071 

0-754 

0-835 

I2.OI 

0.031 

0-330 

0.378 

11.02 

4291.630 

O.II4 

1.  211 

1.318 

I3-I5 

0.072 

0.764 

0.845 

12.15 

0.031 

0.330 

0.378 

1  1.  02 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1908. 


75 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  117.,.     1908,  May  26,  I2h  onl  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.6  mm.     Quality,  good. 


P-P 


O 

o-n 
p 

D 


6S-3 
350-8 

17.4 
—  i.i 


Diameter  168.7  torn 
Factor        1.019 


0.6 

14.1 

14.1 

7S-9 

4-7 

.003 

29.6 

29.6 

60.4 

2-3 

.001 

45-4 

45-4 

44.6 

1.6 

.OOO 

60.6 

60.6 

29.4 

1.4 

.OOO 

75-6 

75-6 

14.4 

1.2 

.000 

90.6 

0.6 

-0.6 

I.I 

.OOO 

<t>  =   ' 

-  o°6 

0  = 

14^4 

0  = 

2Q?4 

X 

A 

V 

•  +  », 

i 

A 

V 

V  +  D, 

f 

A 

t> 

»  +  », 

i. 

km 

km 

0 

km 

km 

° 

km 

km 

° 

4196.699 

0.174 

1.898 

2.032 

14-43 

O.I  60 

1-745 

1.878 

13-77 

0.138 

.506 

1.631 

13-30 

4197.257 

0.173 

1.887 

2.021 

14.36 

o.i  60 

1-745 

1.878 

13-77 

0.138 

.506 

1.631 

13-30 

4203.730 

0.176 

I-9I5 

2.049 

14-51 

0.162 

1.760 

I-893 

13.88 

0.142 

•541 

1.666 

13-58 

4207.566 

0.177 

1.924 

2.058 

14.61 

0.162 

I.7S8 

1.891 

13.86 

0.141 

•530 

1-655 

13-49 

4216.136 

0.175 

1.898 

2.032 

14-43 

0.162 

1-757 

1.890 

13.86 

0.140 

•519 

1.644 

13.40 

4220.509 

0.176 

1.907 

2.041 

14.49 

0.162 

1-755 

1.888 

13-84 

0.142 

1-538 

1.663 

13-56 

4232.887 

0.180 

1.942 

2.076 

14.74 

0.162 

1-748 

i.  88  1 

13-79 

0.143 

1-544 

1.669 

13.61 

4233-328 

0.178 

1.920 

2.054 

14.58 

0.164 

1.768 

1.901 

13-94 

0.142 

1-532 

I-657 

13-51 

4257.815 

0.180 

1.929 

2.063 

14.65 

0.165 

1.768 

I.QOI 

13-94 

0.144 

1-538 

1.663 

13-56 

4258.477 

0.180 

1.928 

2.062 

14.64 

0.163 

1-747 

1.  880 

13-78 

0.144 

J-537 

1.662 

13-55 

4265.418 

0.180 

1.924 

2.058 

14.61 

0.164 

J-753 

1.886 

13-83 

0.144 

I-536 

1.661 

13-54 

4266.081 

0.181 

1-934 

2.068 

14.69 

o.i  66 

1.769 

1.902 

13-94 

0.144 

1-535 

i.  660 

13-53 

4268.915 

0.181 

1-933 

2.067 

14.68 

0.167 

1-783 

1.916 

14.05 

0.145 

1-545 

1.670 

13.61 

4276.836 

0.181 

1.929 

2.063 

14.65 

0.168 

1.790 

1.923 

14.10 

0.145 

i  -544 

1.669 

13.61 

4283.169 

0.182 

1.936 

2.070 

14.70 

o.i  66 

1-765 

1.898 

13-91 

o.!44 

1-532 

1-657 

13-51 

4284.838 

0.182 

1.936 

2.070 

14.70 

0.168 

1.786 

1.919 

14.07 

0-143 

•521 

1.646 

13-42 

4287.566 

0.180 

I-9I3 

2.047 

J4-54 

0.165 

I-756 

1.889 

13-85 

0.145 

•543 

1.668 

13.60 

4288.310 

0.182 

1-935 

2.069 

14.69 

0.167 

1.777 

1.910 

14.00 

0.147 

-564 

1.689 

13-77 

4289.525 

0.182 

1-934 

2.068 

14.69 

0.168 

1.786 

1.919 

14.07 

0.146 

•552 

1.677 

13-67 

4290.377 

0.182 

1-933 

2.067 

14.68 

o.i  66 

1.764 

1.897 

13-91 

0.145 

•541 

1.666 

13-58 

4290.542 

0.180 

1.922 

2.056 

14.60 

o.i  68 

1.784 

1.917 

14.05 

0.149 

.582 

1.707 

13-91 

4291.630 

0.183 

1.942 

2.076 

14-74 

0.166 

1.764 

1.897 

13-91 

0.148 

•572 

1.697 

13-83 

(f>  = 

44°.6 

0  = 

6o!4 

0  = 

7S°.9 

4196.699 

0.108 

.180 

.287 

12.84 

0.069 

0-753 

0.834 

11.99 

0.029 

0.317 

0-365 

10.64 

4197.257 

0.108 

.181 

.288 

12.85 

0.068 

0.742 

0.823 

11.84 

0.030 

0.327 

0-375 

10.93 

4203.730 

O.IIO 

•'93 

.300 

12.97 

0.070 

0.762 

0.843 

12.12 

0.029 

0.317 

0-365 

10.64 

4207.566 

0.109 

.183 

.290 

12.87 

0.068 

0-739 

0.820 

11.79 

0.031 

0-335 

0-383 

ii.  16 

4216.136 

0.108 

.172 

.279 

12.76 

0.066 

0.722 

0.803 

ii-SS 

0.030 

0-325 

0-372 

10.84 

4220.509 

O.IIO 

.190 

.297 

12.94 

0.069 

0.748 

0.829 

11.92 

0.030 

0.325 

0-372 

10.84 

4232-887 

0.109 

•177 

.284 

12.81 

0.071 

0.767 

0.848 

12.19 

0.031 

0-334 

0.382 

11.13 

4233-328 

O.IIO 

.187 

.294 

12.91 

0.070 

0.756 

0.837 

12.04 

0.029 

0.314 

0.362 

10.55 

4257-8IS 

O.III 

.189 

.296 

12.93 

0.074 

0.791 

0.872 

12.54 

0.032 

0-344 

0-392 

"•43 

4258.477 

O.III 

.188 

•295 

12.92 

0.072 

0.770 

0.851 

12.24 

0.032 

0-343 

0.391 

"•39 

4265.418 

O.IIO 

.178 

-285 

12.82 

0.071 

0.760 

0.841 

12.09 

0.031 

0-333 

0.381 

II.  IO 

4266.081 

O.II2 

1.194 

.301 

12.98 

0.072 

0.769 

0.850 

12.22 

0.032 

0-343 

0.391 

"•39 

4268.915 

O.II2 

I-I93 

•300 

12.97 

0.072 

0.768 

0.849 

12.21 

0.032 

0-343 

o.39i 

"•39 

4276.836 

O.II2 

I-I93 

.300 

12.97 

0.071 

0.758 

0.839 

I2.O7 

0.032 

0.342 

0.390 

"•37 

4283.169 

O.III 

1.181 

.288 

12.85 

0.072 

0.770 

0.851 

12.24 

0.032 

0.342 

0.390 

"•37 

4284.838 

O.I  1  2 

1.194 

.301 

12.98 

0.072 

0.769 

0.850 

12.22 

0.032 

0-344 

0.392 

"•43 

4287.566 

O.II2 

I-I93 

.300 

12-97 

0.073 

0.779 

0.860 

12.36 

0.033 

0-354 

0.402 

11.72 

4288.310 

O.II3 

1.203 

.310 

13-07 

0.073 

0-777 

0.858 

12-33 

0.032 

0-343 

0-391 

"•39 

4289.525 

O.I  1  2 

1.191 

.298 

12.95 

0.073 

0.777 

0.858 

12-33 

0.033 

0-353 

0.401 

11.69 

4290.377 

O.II4 

1.  211 

.318 

I3-I5 

0.072 

0.767 

0.848 

12.19 

0.032 

0-343 

0.391 

"•39 

4290.542 

O.II4 

1.  211 

-3l8 

13-15 

0.073 

0.776 

0-857 

12.32 

0.032 

0-343 

0-391 

n-39 

4291.630 

O.II3 

I.2OO 

•307 

13-04 

0.074 

0.786 

0.867 

12.47 

0-033 

0-352 

0.400 

11.66 

76      AN   INVESTIGATION  OF  THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 

Plate  w  I20j.     1908,  June  2,  3h  iom  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.2  mm.     Quality,  good. 

p  —  P          T  0  T] 


Q        71-7 

12.7 

12.7 

77-3 

1.6 

i.ooo 

0-0    357.2 

26.2 

26.2 

63.8 

0.8 

1.  000 

P          15-0 

41.7 

41.7 

48.3 

o-S 

I.OOO 

D        -0.3 

57-2 

57-2 

32.8 

0.4 

I.OOO 

Diameter  168.0  mm 

72.7 

72.7 

17-3 

0.4 

I.OOO 

Factor        1.014 

87.7 

87.7 

2-3 

0.4 

I.OOO 

102.7 

102.7 

-12.7 

0.4 

I.OOO 

»--.* 

0  =  2?3 

0  =  i??3 

A 

' 

ti  +  »j 

I 

A 

V 

.  +  „ 

« 

A 

11 

V  -f-  V 

f 

4196.699 

o.i  66 

km 

.802 

km 
1.932 

14.06 

0.175 

km 
1.894 

km 

2.028 

14.41 

0.158 

km 

•715 

km 
1.846 

13-74 

4197-257 

o.i  66 

.801 

•931 

14.05 

0.176 

1.904 

2.038 

14.48 

0.158           .715 

1.846 

13-74 

4203.730 

o.i  66 

.798 

.928 

14-03 

0.175 

1.893 

2.027 

14.40 

0.161 

•739 

1.870 

I3-92 

4207.566 

0.169 

.825 

•955 

14-23 

0.175 

1.893 

2.027 

14.40 

0.160 

.728 

1.859 

13.84 

4216.136 

o.i  68 

.813 

•943 

14.14 

0.176 

1.899 

2-033 

14.44 

0.160 

.726 

1-857 

13.82 

4220.509 

0.170 

.832 

.962 

14.28 

0.178 

1.918 

2.052 

14.58 

0.161 

•735 

1.866 

13.89 

4232.887 

0.170 

.825 

•955 

14-23 

0.180 

1.932 

2.066 

14.67 

0.162 

.740 

1.871 

13-93 

4233-328 

0.170 

.825 

•955 

14-23 

0.180 

I-93I 

2.065 

14.67 

0.164 

•759 

1.890 

14.07 

4257-815 

0.173 

.841 

.971 

14-34 

0.180 

1.912 

2.046 

14-54 

0.162 

•724 

1.855 

13.80 

4258.477 

0-173 

.841 

•97i 

14-34 

0.182 

I-93I 

2.065 

14.67 

0.162 

•724 

1.855 

13.80 

4265.418 

0.172 

.829 

•959 

14.26 

0.182 

1.930 

2.064 

14.66 

0.163 

•733 

1.864 

13.88 

4266.081 

0.173 

.841 

.971 

14-34 

0.182 

1.928 

2.062 

14.65 

0.160 

.701 

1.832 

13.64 

4268.915 

0.174 

.850 

.980 

14.41 

0.180 

1.909 

2.043 

14.51 

0.164 

•739 

1.870 

13.92 

4276.836            0.169 

•793 

•923 

13-99 

0.180 

1.908 

2.042 

I4-5I 

0.165 

1.746 

1.877 

13-97 

4283.169 

0.173 

•830 

.960 

14.26 

0.182 

1.927 

2.061 

14.64 

0.164 

I-736 

1.867 

13.90 

4284.838 

0-173 

•830 

.960 

14.26 

0.182 

I-925 

2.059 

14-63 

0.164 

1-734 

1.865 

13.88 

4287.566 

0.173 

.829 

•959 

14.26 

0.182 

I-925 

2.059 

14.63 

0.164 

•734 

1.865 

13.88 

4288.310 

0.174 

•843 

•973 

14-36 

0.183 

J-935 

2.069 

14.70 

0.165 

•743 

1.874 

13-95 

4289.525 

0.174 

.841 

.971 

14-34 

0.182 

1.923 

2.057 

14.62 

0.165 

.742 

1-873 

13-94 

4290-377 

0-173 

•830 

.960 

14.26 

0.184 

1-943 

2.077 

14.76 

0.164 

•732 

1.863 

13-87 

4290.542 

0.176 

.860 

.990 

14.48 

0.183 

J-933 

2.067 

14.69 

0.164 

•732 

1.863 

13-87 

4291.630 

0.176 

.860 

.990 

14.48 

0.182 

1.923 

2.057 

14.62 

0.162 

.712 

1.843 

I3-72 

0  =  32°.& 

0=48!3 

0  =  63^8 

0  =  7?!3 

_ 

A 

D 

.+,, 

f 

A 

V 

,  +  ,, 

1 

A 

• 

•>  +  », 

* 

A 

' 

.  +  ,, 

« 

4196.699 

0.139 

km 
1.499 

km 

1.618 

o 

13-67 

0.096 

km 

1.042 

km 

•143 

12.20 

0.051 

km 

0-555 

km 

0.628 

IO.IO 

0.026 

km 

0.282 

km 

0.32; 

10.56 

4I97-257 

0.138 

1.498 

1.617 

13.66 

0.096 

.042 

•143 

12.20 

0-053 

0-575 

0.648 

10.42 

0.026 

0.282 

0.323 

10.56 

4203.730 

0.140 

1.516 

1-635 

13.81 

0.098 

.061 

.162 

12.40 

0.052 

0-563 

0.636 

10.23 

0.027 

0.292 

0-335 

10.88 

4207.566 

0.141 

1.521 

1.640 

13-85 

0.098 

.061 

.16: 

I2.4O 

0.052 

0.562 

0.635 

IO.2I 

0.027 

0.291 

10.85 

4216.136 

0.139 

1.501 

1.620 

13-68 

0.098 

•057 

•IS* 

12.36 

0.052 

0.561 

0.634 

IO.2O 

0.026 

0.280 

0-325 

10.50 

4220.509 

0.141 

1.520 

1.639 

13.84 

0.102 

.099 

.2OC 

12.81 

0-053 

0.570 

0-643 

10-34 

0.025 

0.270 

0-315 

10.17 

4232.887        0.142 

1-524 

1.643 

13.88 

O.IOO 

•073 

.174 

12.5.3 

0-053 

0.569 

0.642 

10-33 

0.028 

0.300 

0-345 

11.14 

4233-328 

0.142 

I-S24 

1-643 

13-88 

O.IOO 

•073 

.174 

12-53 

0.053 

0-569 

0.642 

10-33 

0.028 

0.300 

0-345 

11.14 

4257-815 

0.144 

1-535 

1.654 

13-97 

O.IOI 

•075 

.176 

12-55 

0-053 

0-565 

0.638 

IO.26 

0.028 

0.297 

0.342 

11.04 

4258.477 

0.142 

1.511 

1.630 

13-77 

0.102 

-085 

.l8« 

12.66 

0.052 

0-555 

0.638 

10.26 

0.027 

0.287 

0-332 

10.72 

4265.418 

0.143 

1.521 

1.640 

13-85 

O.IOO 

1.064 

1.165 

12.43 

0.054 

0-574 

0.647 

10.41 

0.028 

0.297 

0.342 

11.04 

4266.081 

0.144 

I-525 

1.644 

13.89 

0.103 

1.095 

I.I9<j 

12.76 

0.054 

0-374 

0.647 

IO.4I 

0.029 

0.307 

0.352 

11-37 

4268.915 

0.144 

1-525 

1.644 

13.89 

O.IOI 

1-073 

I.I74 

12.53 

0-055 

0-583 

0.656 

10-55 

0.028 

0.296!    0.341 

1  1.  or 

4276.836 

0.144 

1-524 

1.643 

13.88 

O.IOO 

1.061 

I.I62 

12.40 

0.053 

0.562 

0.635 

10.21 

0.028 

0.296 

o.34i 

II.OI 

4283.169 

0.144 

1-524 

1.643 

13.88 

O.IOO 

1.059 

1.160 

12.38 

0.054 

0.571 

0.644 

10.36 

0.028 

0.296 

0.341 

1  1.  01 

4284.838 

0.145 

1-534 

I-653 

13.96 

O.IO2 

1.080 

1.186 

12.66 

0.054 

0.571 

0.644 

10.36 

0.028 

0.296 

0.341 

II.  OI 

4287.566 

0.146 

•544 

1.663 

14.04 

O.IOO 

1.058 

.155 

12.37 

0-054 

0.571 

0.644 

10.36 

0.025 

0.265 

0.310 

IO.OI 

4288.310 

0.146 

•544 

1.663 

14.04 

0.103 

1.089 

.190 

12.70 

0-053 

0.560 

0.633 

IO.I8 

0.028 

0.295 

0.340 

10.98 

4289.525 

0.146 

•543 

1.662 

14.04 

0.103 

1.089 

.190 

12.70 

0.053 

0.560 

0.633 

IO.I8 

0.028 

0.295 

0.340 

10.98 

4290-377 

0.146 

•543 

1.662 

14.04 

0.102 

1.078 

•i79 

12.58 

0-053 

0.560 

0-633 

IO.I8 

0.028 

0.295 

0.340 

10.98 

4290.542 

0.146 

•543 

1.662 

14.04 

0.104 

1.099 

.200 

12.81 

0.055 

0.580 

0-653 

10.50 

0.027 

0.285 

10.66 

4291.630 

0.147 

•553 

1.672 

14.12 

0.104 

1.099 

.2OC 

12.81 

0.053 

0.560 

0-633 

IO.I8 

0.026 

0.275 

0.320 

10.33 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1908. 


77 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  a  120.,.     1908,  June  2,  3h  iom  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.2  mm.     Quality,  good. 

p  —  P  TT  <t>  1) 


10.7 

10.7 

79-3 

1.6 

.000 

Q         71.7 

24.2 

24.2 

65.8 

0.8 

.000 

o-n   357.2 

39-7 

39-7 

50.3 

0-5 

.000 

P        15-0 

5S-2 

55-2 

34-8 

0.4 

.000 

D         -0.3 

70.7 

70.7 

19-3 

0.4 

.000 

Diameter  168.0  mm 

85.7 

4-3 

o-4 

.000 

Factor        1.014 

100.7 

100.7 

-10.7 

0.4 

.000 

\ 

*--«* 

*-A 

4>  =  I9?3 

A 

A 

' 

f  +  »! 

« 

A 

t> 

f  +  », 

£ 

A 

D 

.+,, 

1 

4196.699 

0.170 

km 
1.844 

km 
1-974 

14.26 

0.175 

km 

.900 

km 
2.034 

14.48 

0.156 

km 
•693 

km 

1.824 

13-74 

4197-257 

0.170 

1-844 

1-974 

14.26 

0.176 

.910 

2.044 

14-56 

0.156 

•693 

1.824 

13-74 

4203.730 

0.172 

1.862 

1.992 

14-39 

0.177 

.916 

2.050 

14.60 

0.159 

.722 

I-853 

13.96 

4207.566 

0.173 

1.872 

2.002 

14.46 

0.176 

.904 

2.038 

14-51 

o.i  60 

•731 

1.862 

14.02 

4216.136 

0.174 

1.877 

2.007 

14-50 

0.174 

.878 

2.OI2 

14-33 

0.157 

•693 

1.824 

13-74 

4220.509 

0.176 

I-897 

2.O27 

14-64 

o.i  So 

.940 

2.074 

14-77 

o.i  60 

.719 

1.850 

13-93 

4232.887 

0.176 

1.888 

2.018 

14-58 

0.178 

.910 

2.044 

14-56 

0.159 

•707 

1.838 

13-84 

4233-328 

0.174 

1.867 

1.997 

14-43 

0.178 

.910 

2.044 

14-56 

o.i  60 

•717 

1.848 

13-92 

4257-815 

0.177 

1.887 

2.017 

14-57 

0.181 

.918 

2.052 

14.61 

0.161 

.708 

1.839 

13-85 

4258.477 

0.176 

1.876 

2.OO6 

14.49 

0.180 

.908 

2.042 

14-54 

0.161 

.707 

1.838 

13.84 

4265.418 

0.177 

1.887 

2.OI7 

14.57 

0.180 

.904 

2.038 

14-51 

o.i  60 

•697 

1.828 

13-77 

4266.081 

0.177 

1.886 

2.016 

14.56 

0.181 

.916 

2.050 

14.60 

0.162 

.716 

1.847 

13-91 

4268.915 

0.178 

1.896 

2.026 

14.64 

0.180 

.906 

2.040 

14-53 

0.162 

•715 

1.846 

13.90 

4276.836 

0.176 

1.867 

1.997 

14-43 

0.180 

•905 

2.039 

14-52 

o.i  60 

.694 

1.825 

13-75 

4283.169 

0.178 

1.884 

2.OI4 

14-55 

0.180 

•904 

2.038 

14-51 

0.162 

•715 

1.846 

13.90 

4284.838 

0.179 

1.894 

2.024 

14.62 

0.181 

.916 

2.050 

14.60 

0.161 

.704 

1.835 

13.82 

4287.566 

0.176 

1.862 

1-992 

14-39 

0.180 

.904 

2.038 

14-51 

0.162 

.714 

1-845 

13-90 

4288.310 

0.179 

1.893 

2.023 

14.62 

0.180 

•903 

2.037 

14.50 

0.163 

.724 

1.855 

13-97 

4289.525 

0.178 

1.882 

2.OI2 

14-54 

0.180 

.902 

2.036 

14-50 

o.i  60 

•693 

1.824 

13-74 

4290.377 

0.178 

1.882 

2.012 

14.54 

0.179 

.892 

2.026 

14-43 

0.161 

.704 

1-835 

13.82 

4290.542 

0.179 

1.891 

2.O2I 

14.60 

0.182 

.922 

2.056 

14.64 

0.163 

.724 

1.855 

13-97 

4291.630 

0.179 

1.891 

2.O2I 

14.60 

0.180 

.901 

2-035 

14.49 

0.162 

•712 

1.843 

13-88 

0=34:8 

.=50:3 

*-6S:8 

<t>  =  79?3 

A 

V 

t>  +  z>i 

£ 

A 

11 

f  +  t>, 

• 

A 

V 

,  +  ,, 

« 

A 

V 

.  +  ,, 

£ 

km 

km 

0 

km 

km 

0 

km 

km 

o 

km 

km 

0 

4196.699 

0.136 

1-475 

1-594 

13.78 

0.095 

1.030 

I.I28 

12.54 

0.057 

O.62I 

0.68? 

"•93 

0.019 

0.206 

0-245 

9-37 

4197-257 

0.136 

1.476 

1-595 

13-79 

0.096 

1.039 

I-I37 

12.64 

0.058 

0.630 

0.698 

12.09 

0.019 

0.206 

0-245 

9-37 

4203.730 

0.138 

1.490 

1.  60? 

13-91 

0.098 

1.062 

l.IOC 

12.89 

0.058 

0.626 

0.694 

12.02 

O.O2O 

0.216 

0-255 

9-75 

4207.566 

0.138 

1.488 

1.605 

13.89 

0.098 

1.061 

1.159 

12.88 

0.058 

0.626 

0.694 

12.  02 

0.020 

0.215 

0.254 

9.71 

4216.136 

0.136 

1.467 

1.58^ 

53.71 

0.097 

1.044 

1.142 

12.69 

0.058 

0.625 

0.693 

I2.OO 

O.O2O 

0.215 

0.254 

9.71 

4220.509 

0.139 

1-493 

1.61; 

13-94 

0.099 

1.065 

1.163 

12.93 

0.058 

0.625 

0.693 

I2.OO 

O.O2O 

0.215 

0.254 

9.71 

4232.887 

0.140 

1.502 

1.621 

14.01 

0.099 

1.063 

1.161 

12.90 

0.058 

0.623 

0.691 

11.97 

0.020 

0.215 

0.254 

9-71 

4233-328 

0.140 

1.502 

.621 

14.01 

0.098 

1.052 

1.150 

12.78 

0.056 

0.601 

0.669 

"•59 

0.019 

0.204 

0.243 

9.29 

4257-815 

0.142 

1-505 

.624 

14.04 

O.IOO 

1.067 

1.165 

12-95 

0.060 

0.639 

0.707 

12.24 

O.O22 

0.234 

0-273 

10.44 

4258.477 

0.140 

1.483 

.605 

13-85 

O.IOO 

1.066 

1.164 

12.94 

0.060 

0.639 

0.707 

12.24 

O.O2O 

0.213 

0.252 

9.64 

4265.418 

0.141 

1.492 

.611 

13-93 

O.IOI 

1.071 

i.i6c 

12.99 

0.059 

0.628 

0.696 

12.05 

0.021 

0.223 

0.262 

IO.O2 

4266.081 

0.141 

1-492 

.611 

13-93 

O.IOI 

1.071 

1.169 

12-99 

0.060 

0-635 

0.703 

12.  l8 

O.O2O 

0.213 

0.252 

9.64 

4268.915 

0.140 

1.482 

.601 

13.84 

0.099 

1-053 

1.151 

12.79 

0.060 

0.635 

0.703 

12.  l8 

O.O2O 

O.2I2 

0.251 

9.60 

4276.836 

0.142 

I-503 

.622 

14.02 

O.IOO 

1-059 

i-i57 

12.86 

0.060 

0.635 

0-703 

12.18 

0.021 

0.223 

0.262 

IO.O2 

4283.169 

0.140 

1.481 

.6oc 

13-83 

O.IOO 

1.059 

I-I57 

12.86 

0-057 

0-593 

0.661 

"•45 

0.020 

0.212 

0.251 

9-6o 

4284.838 

0.142 

I-504 

.623 

14-03 

O.IO2 

1.079 

1.177 

13.08 

0.059 

0.625 

0.693 

I2.OO 

O.O2O 

O.2II 

0.250 

9.56 

4287.566 

0.141 

1.492 

.611 

13-93 

O.IOO 

1.058 

1.156 

12.85 

0.060 

0.635 

0.703 

12.18 

0.022 

0.232 

0.271 

10.36 

4288.310 

0.142 

1.502 

.621 

14.01 

O.IO2 

1.078 

1.176 

13-07 

0.059 

0.624 

0.692 

11.98 

0.024 

0-253 

0.292 

ii.  16 

4289.525 

0.141 

1.491 

.6ic 

13.92 

O.1O2 

1.078 

1.176 

13-07 

0.059 

0.624 

0.692 

11.98 

O.O24 

0-253 

0.292 

u.  16 

4290.377 

0.140 

1.480 

1-599 

13.82 

O.IOI 

1.067 

1.165 

12.95 

0.058 

0.615 

0.683 

11.83 

0.022 

0.232 

0.271 

10.36 

4290.542 

0.142 

1.500 

1.619 

14.00 

O.IOI 

1.067 

1.165 

12.95 

0.059     0.624 

0.692 

12.98 

0.020 

0.21  1 

0.250 

9-56 

4291.630 

0.142 

1.500 

1.619 

14.00 

O.IOO 

1-057 

12.84 

0.062    0.616 

0.684 

11.83 

O.O22 

0.232 

0.271 

10.36 

78      AN   INVESTIGATION   OF   THE   ROTATION  PERIOD   OF  THE   SUN  BY  SPECTROSCOPIC  METHODS. 


TABLE  u.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  I28r     1908,  June  9,  I2h  50™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.5  mm.     Quality,  good. 


p-f 


Q 

Q-a 
p 

D 


78.7 
4-2 

12. 1 

0.6 


Diameter  166.0  mm 
Factor        1.018 


0.5 

15-5 

iS-5 

74-5 

2.O 

I.OOI 

30-5 

30-S 

59-5 

I.O 

I.OOO 

45-5 

45-5 

44-S 

0.7 

1.  000 

60.5 

60.5 

29-S 

0.6 

i.ooo 

75-5 

75-5 

14-5 

0.6 

I.OOO 

90-5 

9°-5 

-o-S 

0.6 

I.OOO 

0  = 

-o!s 

0  = 

u:s 

0  = 

29!5 

A 

• 

.-M, 

i 

A 

t> 

»+», 

« 

A 

V 

.  +  ., 

i 

4196.699 

0.174 

km 
1.897 

km 
2.031 

14.42 

0.164 

km 

1.787 

km 
.917 

0 

14.06 

0.143 

km 
1.560 

km 

1.684 

13-74 

4197-257 

0.174 

.896 

2.030 

14.41 

0.162 

1.776 

.906 

13.98 

0.144 

1.569 

1.693 

13.81 

4203-730 

0.176 

.914 

2.048 

14-54 

0.164 

1.778 

.908 

13-99 

0.144 

I-556 

1.  680 

13-70 

4207-566 

0.177 

•923 

2.057 

14.61 

0.163 

1.768 

.898 

13.92 

0-145 

1.565 

1.689 

13-76 

4216.136 

0.175 

.896 

2.030 

14.41 

0.162 

1-757 

.887 

13.84 

0.145 

I-565 

1.689 

13-76 

4220.509 

0.177 

.910 

2.044 

14-51 

0.165 

1.782 

.912 

14.02 

0.144 

1-554 

1.678 

13-70 

4232.887 

0.177 

.907 

2.041 

14.49 

0.166 

1.787 

.917 

14.06 

0.145 

1.564 

1.688 

13-78 

4233-328 

0.178 

.918 

2.052 

14-57 

0.166 

1.787 

.917 

14.06 

0.146 

1-573 

1.697 

13-85 

4257-8I5 

0.182 

•949 

2-083 

14.79 

o.i  68 

1-795 

•925 

14.12 

0.148 

1-574 

1.698 

13-85 

4258.477 

0.181 

•935 

2.069 

14.69 

0.169 

i.  808 

•938 

14.21 

0.146 

1-554 

1.678 

13-70 

4265.418 

o.i  80 

•923 

2-057 

14.61 

0.167 

1-777 

.907 

13.98 

0.146 

1-553 

1.677 

13.69 

4266.081 

0.182 

•943 

2.077 

14-75 

o.i  68 

1.787 

.917 

14.06 

0.147 

1.564 

1.688 

13.78 

4268.915 

0.181 

•929 

2.063 

14-65 

0.167 

1.779 

.909 

14.00 

0.146 

'•553 

1.677 

13.69 

4276.836 

0.181 

.928 

2.062 

14.64 

0.167 

1-779 

.909 

14.00 

0.146 

1-552 

1.676 

13.68 

4283.169 

0.183 

•945 

2.079 

14.76 

0.170 

1.810 

•940 

14-23 

0.147 

1.562 

1.686 

13-75 

4284.838 

0.182 

•933 

2.067 

14.68 

o.i  68 

1.784 

.914 

14.04 

0.146 

1-550 

1.674 

13-67 

4287.566 

0.180 

.912 

2.046 

14-50 

0.169 

1.794 

.924 

14.11 

0.147 

1.560 

1.684 

13-75 

4288.310 

0.181 

•923 

2.057 

14.61 

0.169 

1-794 

.924 

14.11 

0.148 

i-S7o 

1.694 

13-83 

4289.525 

0.182 

•932 

2.066 

14.67 

o.i  68 

1-783 

•913 

14-03 

0.148 

J-570 

1.694 

13-83 

4290.377 

0.181 

.921 

2-055 

14-59 

0.170 

1.805 

•935 

14.19 

0.146 

1-549 

1-673 

13-65 

4290.542 

0.182 

1-93' 

2.065 

14.66 

0.169 

1-793 

•923 

14.10 

0.151 

i.  60  1 

1-725 

14.08 

4291-630 

0.182 

I-93I 

2.065 

14.66 

0.169 

1-793 

1.923 

14.10 

0.149 

1.581 

1-705 

13-91 

0  = 

44?S 

0  = 

S9?5 

0  = 

74!5 

4196-699 

0.105 

1.146 

.252 

12.46 

0.070 

0.763 

0.845 

11.82 

0.030 

0.327 

0-379 

10.07 

4197-257 

o.i  06 

1.155 

.261 

12.55 

0.068 

0.741 

0.823 

11.51 

0.028 

0.306 

0.358 

9-51 

4203.730 

0.108 

1.171 

.277 

12.71 

0.070 

0.762 

0.844 

11.81 

0.030 

0.326 

0-378 

10.04 

4207.566 

0.108 

1.171 

•277 

12.71 

0.070 

0.760 

0.842 

11.78 

0.030 

0.326 

0-378 

10.04 

4216.136 

o.i  06 

1.149 

•255 

12.49 

0.068 

0-737 

0.819 

"•45 

0.029 

0.314 

0.366 

9.72 

4220.509 

0.108 

1.166 

1.272 

12.66 

0.070 

0-758 

0.840 

"•75 

0.030 

0.325 

0-377 

IO.O2 

4232.887 

0.108 

1.163 

1.269 

12.62 

0.068 

0-733 

0.815 

11.40 

0.031 

0-334 

0.386 

IO.25 

4233-328 

0.107 

I-I53 

1-259 

12-53 

0.068 

0-733 

0.815 

11.40 

0.030 

0.323 

0-375 

9.96 

4257.8I5 

O.IIO 

1.171 

1.277 

12.71 

0.072 

0.770 

0.852 

11.92 

0.031 

0-332 

0.384 

IO.2O 

4258.477 

0.108 

1.151 

1-257 

12.51 

0.071 

0.760 

0.842 

11.78 

0.032 

0-342 

0-394 

10-47 

4265.418 

0.108 

1.151 

1-257 

12.51 

0.069 

0-737 

0.819 

n-45 

0.031 

0-331 

0-383 

10.17 

4266.081 

0.109 

1.161 

.267 

12.  6l 

0.072 

0-755 

0.837 

11.71 

0.031 

0-33' 

0-383 

10.17 

4268.915 

0.107 

1-139 

•245 

12.39 

0.072 

0-755 

0.837 

11.71 

0.030 

0.320 

0.372 

9.88 

4276.836 

0.108 

1.148 

•254 

12.48 

0.070 

0-745 

0.827 

"•57 

0.032 

0-340 

0.392 

10.41 

4283.169 

0.108 

1.148 

•254 

12.48 

0.070 

0-745 

0.827 

"•57 

0.031 

0.329 

0.381 

IO.I2 

4284.838 

0.109 

1.158 

.264 

12.58 

0.069 

0.736 

0.818 

11.44 

0.030 

0.319 

0.371 

9-86 

4287.566 

0.107 

I-I39 

•245 

12.39 

0.070 

0-745 

0.827 

n-57 

0.031 

0.329 

0.381 

IO.I2 

4288.310 

o.i  08 

1.148 

-254 

12.48 

0.072 

0.765 

0.847 

11.85 

0.030 

0.319 

0.371 

9.86 

4289.525 

0.108 

1.147 

•253 

12.47 

0.070 

0-745 

0.827 

11-57 

0.031 

0.329 

0.381 

IO.I2 

4290-377 

0.108 

1.147 

•253 

12.47 

0.069 

0-735 

0.817 

"•43 

0.030 

0.319 

0.371 

9-86 

4290.542 

0.109 

1.156 

.262 

12.56 

0.070 

0-745 

0.827 

"•57 

0.032 

o-339 

0-391 

10.39 

4291.630 

0.109 

1.156 

.262 

12.56 

0.073 

0-775 

0.857 

11.97 

0.034 

0.361 

0-413 

10.97 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1908. 


79 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  132.     1908,  June  10,  8h  15™  G  .M.  T.     Measured  by  L.  on  T.     Distance  from  Limb,  1.4  mm.     Quality,  good. 


sec') 


0.6 

O         79-5 

10.6 

10.6 

79-4 

3-4 

i.  002 

O-n        5.0 

25.6 

25.6 

64.4 

i-5 

I.OOO 

P           11.  7 

40.6 

40.6 

49-4 

I.O 

I.OOO 

D           0.7 

55-6 

55-6 

34-4 

0.8 

I.OOO 

Diameter  165.6  mm 

70.6 

70.6 

19.4 

0.6 

I.OOO 

Factor        1.017 

85.6 

85.6 

4-4 

0.6 

i.ooo 

0  = 

4?4 

0  - 

IQ?4 

<t>  = 

34?4 

X 

A 

V 

»  +  »! 

1 

A 

V 

t  +  », 

£ 

A 

V 

»  +  »[ 

f 

km 

km 

o 

km 

km 

« 

km 

km 

0 

4196.699 

0.172 

1.873 

2.007 

14.29 

0.162 

1.764 

1.895 

14.26 

0-135 

.469 

1-588 

13-66 

4I97-2S7 

0.172 

1.873 

2.007 

14.29 

0.161 

1-753 

.884 

14.18 

0.134 

•459 

1-578 

13-58 

4203.730 

0.176 

1.912 

2.046 

14-57 

0.163 

1.766 

.89? 

14.28 

0.138 

•500 

1.619 

13-93 

4207.566 

0.174 

1.888 

2.O22 

14.40 

0.162 

1-755 

.886 

14.20 

0.138 

•497 

.616 

13-91 

4216.136 

0.174 

1.883 

2.OI7 

14.36 

0.161 

1-743 

.874 

14.10 

0-137 

•485 

.604 

13.80 

4220.509 

0.176 

1.903 

2.037 

14-5° 

0.164 

1-773 

.904 

14-34 

0-137 

.481 

.600 

13-77 

4232.887 

0.178 

1.916 

2.050 

14.60 

0.164 

1-765 

.896 

14.27 

0.136 

•465 

•584 

13-63 

4233-328 

0.178 

1.916 

2.050 

14.60 

0.164 

1-765 

.896 

14.27 

0-137 

•475 

•594 

13.72 

42S7-8IS 

0.177 

1.893 

2.O27 

14-43 

0.167 

1-785 

.916 

14.42 

0.138 

.476 

•595 

13-73 

4258-477 

0.179 

1.912 

2.046 

14-57 

o.i  66 

1-775 

.006 

14-34 

0.138 

•473 

•592 

13-7° 

4265.418 

0.179 

1.910 

2.044 

14.56 

o.i  66 

1.770 

.901 

14-31 

0.138 

.468 

•587 

13.66 

4266.081 

O.I  80 

1.920 

2.054 

14.63 

o.i  66 

1.770 

.901 

14-31 

0.140 

•493 

.612 

J3-87 

4268.915 

O.I  80 

1.912 

2.046 

14-57 

0.165 

1.760 

.891 

14-23 

0.138 

.467 

.586 

13-65 

4276.836 

0.180 

1.912 

2.046 

14-57 

0.167 

1-774 

•90S 

14-35 

0.138 

.466 

•585 

13-63 

4283.169 

0.179 

i.  goo 

2-034 

14.48 

0.167 

1-773 

.904 

14-34 

0.139 

.476 

•595 

13-73 

4284.838 

0.178 

1.890 

2.O24 

14.41 

o.i  66 

1.762 

•893 

14-25 

0-139 

•475 

•594 

I3-72 

4287.566 

0.177 

1.878 

2.OI2 

I4-32 

0.167 

1.771 

.902 

14-32 

0.138 

.464 

.583 

13.62 

4288.310 

0.178 

1.888 

2.022 

14.40 

0.165 

•750 

.881 

14.17 

0.139 

•475 

-594 

13.72 

4289-325 

0.180 

1.908 

2.O42 

14-55 

0.167 

.772 

•9°3 

J4-33 

0.137 

•453 

•572 

13-53 

4290.377 

0.178 

1.887 

2.O2I 

14-39 

0.167 

.770 

.901 

14-31 

0.139 

•475 

•594 

I3-72 

4290.542 

0.180 

1.908 

2.O42 

14-55 

0.167 

.770 

.901 

14-31 

0.142 

•505 

.624 

13.98 

4291.630 

0.177 

1.876 

2.0IO 

I4-3I 

0.168 

.780 

.911 

14.38 

0.141 

•495 

.614 

13.89 

0- 

49?4 

<t>  = 

64^4 

<(>  = 

7Q?4 

4196.699 

0.097 

.056 

.1* 

12.00 

0.060 

0.651 

0.723 

11.88 

O.020 

0.218 

0.258 

9.96 

4I97-2S7 

0.097 

.056 

•155 

12.  6O 

0.058 

0.631 

0.703 

11.56 

O.O2O 

0.218 

0.258 

9.96 

4203.730 

O.IOO 

.086 

.I8S 

12.93 

0.060 

0.651 

0.723 

11.88 

O.O2O 

0.217 

0.257 

9.92 

4207.566 

0.098 

.062 

.l6l 

12.67 

0.060 

0.650 

0.722 

11.87 

0.020 

0.217 

0.257 

9.92 

4216.136 

0.098 

.061 

.160 

12.66 

0.060 

0.649 

0.721 

11.84 

O.Olg 

0.208 

0.248 

9-57 

4220.509 

0.099 

.068 

.167 

12.73 

0.058 

0.627 

0.699 

11.50 

O.O2O 

0.217 

0.257 

9-92 

4232.887 

O.IOO 

.076 

•175 

12.82 

0.060 

0.646 

0.718 

11.80 

0.020 

0.216 

0.256 

9.88 

4233-328 

O.IOO 

.076 

•175 

12.82 

0.060 

0.646 

0.718 

11.80 

O.O2I 

0.226 

0.266 

10.27 

4257-815 

0.099 

.056 

•155 

12.60 

0.06  1 

0.652 

0.724 

11.90 

O.O22 

0.234 

0.274 

10.57 

4258.477 

0.099 

•056 

•155 

12.60 

0.060 

0.638 

0.710 

11.68 

O.O2I 

0.224 

0.264 

10.19 

4265.418 

O.IOO 

.063 

.162 

12.68 

0.060 

0.638 

0.710 

11.68 

0.020 

0.214 

0.254 

9.80 

4266.081 

O.IOI 

•073 

.172 

12.79 

0.059 

0.630 

0.702 

"•54 

O.O22 

0.234 

0.274 

10.57 

4268.915 

O.IOI 

•°73 

.172 

12.79 

0.062 

0.659 

0.731 

I2.O2 

0.022 

0.234 

0.274 

10.57 

4276.836 

0.099 

•054 

•153 

12.58 

0.060 

0.638 

0.710 

n.68 

0.021 

0.224 

0.264 

10.19 

4283.169 

O.IOO 

.062 

.l8l 

12.89 

0.060 

0.638 

0.710 

11.68 

O.O2I 

0.224 

0.264 

10.19 

4284-838 

O.IO2 

.083 

.182 

12.90 

0.060 

0.638 

0.710 

11.68 

O.O2I 

0.224 

0.264 

10.19 

4287.566 

O.IOO 

.061 

.160 

12.66 

0.060 

0.638 

0.710 

11.68 

O.O22 

0.234 

0.274 

10.57 

4288.310 

O.IO2 

.083 

.182 

12.90 

0.06  1 

0.648 

0.720 

11.83 

O.O2I 

0.224 

0.264 

10.19 

4289.525 

0.103 

•°93 

.192 

13.00 

0.062 

0.657 

0.729 

11.98 

O.O2O 

0.214 

0.254 

9.80 

4290.377 

O.IOO 

i.  060 

'       -159 

12.65 

0.060 

0.637 

0.709 

11.66 

0.020 

0.214 

0-254 

9.80 

4290.542 

O.IOI 

1.070 

.169 

12.76 

0.060 

0.637 

0.709 

11.66 

O.O2I 

0.223 

0.263 

10.15 

4291.630 

0.102 

1.081 

.ISO 

12.88 

0.06  1 

0.647 

0.719 

11.82 

O.O22 

0-233 

0.273 

10.54 

8o      AN   INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 


n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1908  —  Continued. 
[Plate  w  134.     1908,  June  u,  3h  om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.5  mm.     Quality,  good. 


P-P 


secy 


O 

o-n 
p 

D 


80.2 

5-7 

11.4 

0.8 


Diameter  168.0  mm 
Factor        1.031 


o-5 

10.5 
2S-S 

10.5 

25-5 

79-5 
64-S 

4.0 
i-7 

1.  002 

I.OOO 

40.5 

40.5 

49-5 

i.i 

1.  000 

55-5 

55-5 

34-S 

o-9 

I.OOO 

70.5 
85-5 

70.5 
85.5 

I9-S 

4-5 

0.7 
0.7 

I.OOO 
I.OOO 

9°-5 

Qo-S 

-o-5 

0.7 

I.OOO 

<t>  =  —  °°.S 

<t>  =  4°.$ 

0  =  IQ?5 

A 

ii 

!)  +  !), 

£ 

A 

t 

11  +  II, 

£ 

A 

n 

V  +  Zlj 

I  f 

km 

km 

km 

km 

0 

km 

km 

0 

4196.699 

0.171 

1.888 

2.  022 

14-36 

0.169 

1.864 

1.998 

14-23 

0.156 

.721 

1.852 

13-95 

4197-257 

0.172 

1.897 

2.031 

14.42 

0.169 

1.864 

1.998 

14-23 

0.156 

.721 

1.852 

13-95 

4203.730 

0.174 

1.914 

2.048 

14-54 

0.170 

1.870 

2.004 

14.27 

0.157 

.727 

1.858 

13-99 

4207.566 

0.173 

1.900 

2-034 

14-45 

0.173 

1.902 

2.036 

14.5° 

0.158 

•737 

1.868 

14.07 

4216.136 

0.174 

1.907 

2.O4I 

14.49 

0.169 

1-855 

1.989 

14.16 

0.156 

.711 

1.842 

13-87 

4220.509 

0.174 

1.905 

2.039 

14.48 

0.172 

1.883 

2.017 

14.36 

o.i  60 

•752 

1.883 

14  18 

4232-887 

0.176 

1.918 

2.052 

14-57 

0.174 

I-OOS 

2.039 

14.52 

o.i  60 

•745 

1.876 

14-13 

4233-328 

0.175 

1.908 

2.O42 

14-50 

0.174 

1.905 

2-039 

14.52 

0.161 

-756 

1.887 

14.21 

4257-815 

0.178 

1.929 

2.063 

14-65 

0.173 

1.875 

2.009 

14-31 

0.161 

•745 

1.876 

14.13 

4258.477 

0.177 

1.914 

2.048 

14-54 

0.174 

1.885 

2.019 

14.38 

o.i  60 

•735 

1.866 

14.05 

4265.418 

0.177 

1.912 

2.046 

14-53 

0-175 

1.891 

2.025 

14.42 

0.160 

•731 

1.862 

14.02 

4266.081 

0.178 

1.918 

2.052 

14-57 

0.175 

1.891 

2.025 

14.42 

o.i  60 

•731 

1.862 

14.02 

4268.915 

0.178 

1.926 

2.060 

14.63 

0.175 

1.889 

2.023 

14.41 

o.i  60 

•730 

i.  86  1 

14.01 

4276.836 

0.179 

1.916 

2.050 

14-55 

0.174 

1-875 

2.009 

14.31 

0.161 

•737 

1.868 

14.06 

4283.169 

0.178 

1.914 

2.048 

H-54 

0.174 

1.871 

2.005 

14.28 

0.158 

•699 

1.830 

13-78 

4284.838 

O.I  80 

1-932 

2.O66 

14.67 

0.175 

1.  880 

2.014 

14.34 

o.i  60 

.721 

1.852 

13-95 

4287.566 

0.178  ' 

1.912 

2.046 

14.53 

0.175 

1.880 

2.014 

14-34 

0.160 

.721 

1.852 

13-95 

4288.310 

0.177 

1.903 

2-037 

14-47 

0.174 

1.870 

2.004 

14.27 

0-159 

.709 

1.840 

13.86 

4289.525 

0.177 

1.902 

2-036 

14.46 

0.175 

1.880 

2.014 

14-34 

0.161 

i-73i 

1.862 

14.02 

4290.377 

0.177 

1.902 

2.036 

14.46 

0.171 

1.869 

2.003 

14.26 

0-159 

1.708 

1.839 

13-85 

4290.542 

0.177 

1.902 

2.036 

14.46 

0-173 

1.858 

1.992 

14.19 

0.162 

1-739 

1.870 

14.08 

4291.630 

0.176 

1.891 

2.025 

14.38 

0.175 

1.878 

2.OI2 

14-33 

0.161 

1.728 

1.859 

14.00 

\ 

<t>  =  34°.S 

<t>  =  49°.S 

<t>  =  &4!S 

0  =  7Q?5 

A 

A 

D 

*  +  «, 

£ 

A 

2 

ZI  +  D! 

£ 

A 

t 

*  +  tl, 

1 

A 

t; 

»  +  »j 

£ 

km 

km 

0 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.130 

•435 

1-555 

13.40 

0.096 

1.058 

I-I57 

12.65 

0.057 

0.629 

0.701 

11.56 

0.019 

O.2IO 

0.250,      9.74 

4197.257 

0.131 

•445 

1.66; 

13.48 

0.096 

1.058 

I-I57 

12.65 

O.O58 

0.619 

0.691 

11.40 

0.022 

0.242 

0.282J    10.99 

4203.730 

0.132 

•453 

i-57; 

13-55 

0.096 

1.056 

I-I55 

12.63 

0.057 

0.627 

0.690 

11.51 

0.020 

0.220 

0.260 

>    10.13 

4207.566 

0.130       .430 

i-55< 

'   13-35 

0.097 

1.  066 

1.165 

12.74 

0.058 

0.638 

0.710 

11.72 

O.O2O 

O.22O 

O.2&C 

>    10.13 

4216.136 

0.132 

.446 

i-56( 

13-49 

0.097 

1.063 

1.162 

12.70 

0.057 

0.625 

0.695 

11.50 

O.OI9 

O.2O9 

0.240 

)     9-70 

4220.509 

0.131 

•435 

1-55; 

13.40 

O.IOO 

1.096 

I-I95 

13.06 

0.058 

0.634 

0.70^ 

11.64 

O.O2O 

0.219 

0.851 

)    10.09 

4232.887 

0.132 

•440 

1.560 

>    13-44 

0.098 

1.  068 

1.167 

12.76 

0.058 

0-633 

0.70; 

11.62 

0.019 

0.208 

0.24; 

!       9.66 

4233-328 

0.132 

•440 

1.560 

>    13-44 

0.098 

1.  068 

1.16; 

12.76 

0.058 

0.633 

0.70; 

11.62 

O.OI9 

O.2O8 

0.24! 

!       9.66 

4257-815 

0-133 

•443 

1-56; 

13-47 

O.IOO 

1.085 

1.184 

12.94 

0.059 

0.639 

0.711 

"•73 

O.O2O 

0.217 

0.25- 

'       10.01 

4258.477 

0-133 

.441 

1.561 

13-45 

0.099 

1.071 

1.170 

I  2.  80 

0.059 

0.639 

0.711 

"•73 

0.021 

0.227 

0.26- 

10.40 

4265.418 

0.132 

.428 

i-54i 

13-34 

0.099 

1.071 

1.170 

12.  80 

0.060 

0.649 

0.721 

11.89 

O.O22 

0.237 

0.27- 

10.79 

4266.081 

0.134 

.448 

1.56! 

!    13-51 

0.098 

1.059 

l.lgt 

12.66 

O.o6o 

0.649 

0.721 

11.89 

O.O22 

0.237 

0.27- 

10.79 

4268.915 

0.132 

•425 

i-54. 

13-31 

0.098 

1.056 

I-I55 

12.63 

O.O6O 

0.649 

0.721 

11.89 

O.O2O 

0.216 

0.25* 

>      9-97 

4276.836 

0.131 

.412 

i-53 

>    13.20 

O.IOO 

1.077 

..XT* 

12.85 

0.059 

0.637 

o-7oc 

11.70 

O.O22 

0.237 

0.27- 

10.79 

4283.169 

0-133 

•431 

i-S5 

13-36 

0.098 

1-055 

1-154 

12.62 

0.059 

0.636 

0.70! 

11.69 

O.O2O 

0.216 

0.25< 

>      9-97 

4284.838 

0.134 

•443 

1-56. 

!     13-47 

0.098 

1-055 

1-154 

12.62 

O.o6o 

0.646 

0.71! 

1     11.84 

O.O2O 

0.215 

0.25. 

9-93 

4287.566 

0-133 

•430 

i-55< 

>     13-35 

O.IOO 

1.074 

1-173 

12.82 

0.058 

0.624 

o.69< 

i     1  1  .48 

0.021 

0.226 

0.26( 

)     10.36 

4288.310 

0.133 

•430 

i-55< 

>     13-35 

0.098 

1-055 

1-151 

12.62 

0.058 

0.624 

o.69( 

11.48 

O.O22 

0.236 

0.27< 

>     10.75 

4289.525 

0.134 

•440 

i.5<x 

>     13-44 

O.IOO 

1-073 

1.172 

12.81 

O.o6o 

0.644 

o.7i( 

>     11.81 

O.02I 

0.226 

0.26( 

>     10.36 

4290.377 

o.i34 

•439 

i-5S< 

)     13-43 

0.098 

1-053 

1-152 

I  2.  60 

0.059 

0.634 

o.7o( 

)     11.64 

0.020 

0.215 

0.25. 

'       9-93 

4290.542 

0.134 

•439 

i-55< 

>     13-43 

0.098 

1.052 

1-151 

12-59 

0.058 

0.623 

0-69. 

11.46 

O.O22 

0.236 

0.27) 

>     10.75 

4291.630 

0-135 

•449 

1.561 

)     I3-52 

O.IOI 

1.084 

1.183 

12-93 

O.o6o 

0.644 

o-7i( 

)     11.81 

O.O2O 

0.215 

0.25. 

'      9-93 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1908. 


8l 


TABLE  u.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 

Plate  w  135,.     1908,  June  n,  4h  5om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  2.1  mm.     Quality,  good. 

p— P         *  <t>  i          seci 


o-S 

O         80.2 

10.5 

10.5 

79-5 

4.0 

[.002 

0-11        5.7 

15.5 

iS-S 

74-5 

2.7         i 

.001 

p        11.4 

20.5 

30.5 

59-5 

1.4 

.000 

D           0.8 

45-5 

45  -S 

44-5 

I.O 

.000 

Diameter  167.4  mm 

60.5 

60.5 

29-5 

0.8 

.000 

Factor        i  .026 

75-5 

75-5 

14-5 

0.7 

.000 

90-5 

90-5 

-o-5 

0.7 

.000 

<t>  =  -  °°.s 

<t>  =  14!$ 

<t>  =  2p!s 

X 

A 

V 

f  +  f, 

i 

A 

V 

v  +  vl 

£ 

A 

t> 

•  +  », 

£ 

4196.699 

0-173 

km 
•899 

km 
2-033 

0 

14.44 

0.162 

km 
1.779 

km 
.912 

a 

14.02 

0.141 

km 

1-547 

km 
1.672 

0 

13-64 

4197-257 

0.174 

.910 

2.044 

14.52 

o.i  60 

I-7S6 

.889 

13-35 

0.140 

1-537 

1.662 

13-56 

4203.730 

0.174 

.908 

2.042          I4-5O 

0.164 

1.796 

.929 

14-15 

0.143 

1-565 

1.690 

13-79 

4207.566 

0.174 

.904 

2-038 

14.47 

0.164 

•793 

.926 

14.12 

0-143 

1-565 

1.690 

13-79 

4216.136 

0.177 

•931 

2.065 

14.66 

0.164 

.790 

•923 

14.10 

0.141 

1-539 

1.664 

13-57 

4220.509 

0.176 

1.918 

2.052 

H-57 

0.166 

.809 

1.942 

14.24 

0.143 

1-554 

1.679 

13-70 

4232.887 

0.178 

1-933 

2.067 

14.67 

0.164 

.791 

1.924 

14.11 

0.142 

1-542 

1.667 

13.60 

4233.328 

0.179 

1.942 

2.076 

14.74 

o.i  68 

.824 

1-957 

14-35 

0.142 

1-542 

1.667 

13.60 

4257-815 

0.180 

1.938 

2.072 

14.71 

0.169 

-823 

1.956 

14-34 

0.142 

1.540 

1.665 

13-58 

4258.477 

0.180 

1.936 

2.070 

14.70 

0.170 

-831 

1.964 

14.40 

0-145 

1-564 

1.689 

13-78 

4265.418 

0.178 

I-9I5 

2.049 

14-55 

0.170 

.829 

1.962 

14-39 

0.142 

1-529 

1.654 

13-49 

4266.081 

0.182 

1.963 

2.097 

14.90 

o.i  68 

.807 

1.940 

14-23 

0.146 

1-570 

1.695 

13-83 

4268.915 

0.182 

1-953 

2.087 

14-83 

0.170 

.820 

1-953 

14-32 

0-143 

1-539 

1.664 

13-57 

4276.836 

0.180 

1.928 

2.062 

14.64 

0.169 

.809 

1.942 

14.24 

0.144 

1-545 

1.670 

13.62 

4283.169 

0.182 

1.949 

2.083 

14-79 

o.i  68 

1.798 

i-93i 

14.16 

0.146 

1.562 

1.687 

13.76 

4284.838 

0.180 

1.926 

2.060 

14.63 

0.170 

1.818 

i-95i 

14-31 

0.147 

J-573 

1.698 

13-85 

4287.566 

0.181 

1-935 

2.069 

14.69 

0.171 

1.829 

1.962 

14-39 

0.144 

1-542 

1.667 

13.60 

4288.310 

O.I  80 

1-925 

2.059 

14.62 

0.170 

1.817 

•950 

14.30 

0.146 

1.561 

1.686 

13-75 

4289.525 

0.180 

1.924 

2.058 

14.61 

0.170 

1.820 

•953 

14-32 

0-145 

i-SSi 

1.676 

13.67 

4290.377 

0.180 

1.924 

2-058 

14.61 

o.i  68 

1-797 

•930 

14-15 

0.144 

1.540 

1.665 

13-58 

4200.542 

0.180 

1.924 

2.058 

14.61 

0.170 

1.817 

•950 

14.30 

0.146 

1-553 

1.678 

13.69 

4291.630 

0.180 

1-923 

2.057 

14.60 

0.169 

i.  806 

•939 

14.22 

0.146 

1-553 

1.678 

13.69 

<t>  =  44!s 

0  =  59?5 

0  =  74tS 

<t>  =  7o!s 

A 

V 

»  +  »! 

£ 

A 

V 

f  +  1, 

g 

A 

» 

r  +  »j 

£ 

A 

V 

f  +  t,, 

I 

km 

km 

• 

km 

km 

a 

km 

km 

o 

km 

km 

o 

4196.699 

O.IO2 

1.  122 

1.228 

12.22 

0.060 

0.667 

0.748 

10.46 

0.029 

0.319 

0.370 

9.83 

O.O20 

O.22O 

o.26c 

10.13 

4197-257 

0.103 

I.I30 

1.236 

12.30 

0.062 

0.681 

0.762 

10.66 

0.028 

0.309 

0.360 

9-56 

0.020 

0.220 

0.260 

10.13 

4203.730 

0.104 

I.I38 

1.244 

12.38 

0.064 

0.700 

0.781 

10.92 

0.030 

0.329 

0.380 

10.10 

O.O2I 

0.229 

0.265 

10.48 

4207.566 

O.IO4 

1.136 

1.242 

12.36 

0.063 

0.690 

0.771 

10.78 

0.029 

0.318 

0.360 

9.80 

O.O2I 

0.219 

0.255 

10.09 

4216.136 

O.IO4 

•134 

I.24C 

12.34 

0.063 

0.690 

0.771 

10.78 

0.030 

0.327 

0-37* 

10.05 

0.019 

0.208 

0.24! 

9.66 

4220.509 

0.106 

.156 

1.262 

12.56 

0.063 

0.688 

0.769 

10-75 

0.031 

0-337 

0.388 

10.31 

O.O2O 

0.218 

0.258 

10.05 

4232.887 

0.106 

•151 

1-257 

12.51 

0.064 

0.695 

0.776 

10.85 

0.030 

0.326 

0-377 

IO.O2 

O.O2O 

0.218 

0.258 

10.05 

4233-328 

0.106 

•151 

1-257 

12.51 

0.064 

0.695 

0.776 

10.85 

0.030 

0.326 

0-377 

IO.O2 

0.021 

0.228 

0.268 

10.44 

4257.815 

0.105 

.132 

1.238 

12.32 

0.063 

0.679 

0.760 

10.63 

0.032 

0-344 

0-395 

10.49 

O.O2I 

0.227 

0.267 

10.40 

4258.477 

0.108 

.162 

1.268 

12.62 

0.064 

0.689 

0.770 

10.77 

0.030 

0-324 

0-375 

9-97 

O.O2O 

0.216 

0.256 

9-97 

4265.418 

0.105 

.129 

1-235 

12.29 

0.063 

0.678 

0.758 

10.60 

0.032 

0-344 

Q-395 

10.49 

O.O22 

0.236 

0.276 

10.75 

4266.081 

0.107 

•151 

1-257 

12.51 

0.064 

0.687 

0.768 

10.74 

0.030 

0.324 

0-375 

9-97 

0.020 

0.215 

0.255 

9-93 

4268.915 

0.108 

.l6l 

1.267 

12.  6l 

0.064 

0.687 

0.768 

10.74 

0.032 

0-344 

0-395 

10.49 

O.O22 

0-235 

0.275 

10.71 

4276.836 

0.106 

.136 

1.242 

12.36 

0.064 

0.687 

0.768 

10.74 

0.031 

0-334 

0-385 

10.23 

O.O2I 

0.225 

0.265 

10.32 

4283.169 

0.106 

-134 

1.240 

12-34 

0.066 

0.707 

0.788 

1  1.  02 

0.030 

0.322 

0-373 

9.91 

0.022 

0-235 

0-275 

10.71 

4284.838 

0.106 

•134 

1.240 

12-34 

0.064 

0.687 

0.768 

10.74 

0.032 

0-344 

0-395 

10.49 

O.O2I 

0.224 

0.264 

10.28 

4287.566 

0.107 

.144 

1.  250 

12.44 

0.064 

0.687 

0.768 

10.74 

0.031 

0-334 

0.385 

10.23 

O.O2I 

O.224 

0.264 

10.28 

4288.310 

0.106 

•133 

1.239 

12-33 

0.066 

0.707 

0.788 

1  1.  02 

0.032 

0-343 

0.394     10.46 

0.021 

0.224 

0.264 

10.28 

4289.525 

0.108 

•154 

1.260 

12-54 

0.066 

0.707 

0.788 

1  1.  02 

0.030 

0.321 

0-372 

9.88 

0.020 

0.213 

0-253 

9-85 

4290.377 

0.105 

-123 

1.221) 

12.23 

0.064 

0.687 

0.768 

10.74 

0.030 

0.321 

0.372 

9.88 

O.O2O 

0.213 

0.253 

9.85 

4290.542 

0.104 

•"3 

I.2I5 

12.13 

0.066 

0.705 

0.786 

10.99 

0.032 

0.342 

0-393 

10.43 

0.020 

0.213 

0-253 

9-85 

4291.630 

0.106 

.132 

1.238 

12.32 

0.066 

0.705 

0.786 

10.99 

0.030 

0.321 

0.372 

9.88 

0.022 

0.234 

0.274 

10.69 

8 2      AN  INVESTIGATION   OF   THE  ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC  METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1908  —  Continued. 

Plate  w  135.,.     1908,  June  ii,  4h  50™  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  1.8  mm.    Quality,  good. 

p— P          T-  <t>  i]          secy 


o-S 

O         80.2 

10.5 

10.5 

79-5 

4.0 

i.  002 

G-n      s-7 

iS-5 

iS-5 

74-5 

2.7 

1.  001 

p        11.4 

30-5 

3°-S 

59-5 

i-4 

I.OOO 

D            0.8 

45-5 

45-5 

44-S 

I.O 

I.OOO 

Diameter  167.4  mm 

60.5 

60.5 

29-5 

0.8 

I.OOO 

Factor        1.022 

75-5 

75-5 

I4-S 

0.7 

I.OOO 

90-5 

90-5 

-o-S 

0.7 

I.OOO 

0  =  -  o?s 

0  =  I4!S 

0  =  29°.S 

X 

A 

V 

.  +  * 

1 

A 

D 

.  +  ., 

* 

A 

D 

.  +  ,, 

« 

4196.699 

0.171 

km 

1.872 

km 
2.006 

14.24 

0.161 

km 
1.762 

km 
1.895 

13.90 

0.141 

km 
1-542 

km 
1.667 

13-60 

4197-257 

0.172 

1.881 

2.015 

14-31 

0.162 

1.771 

1.904 

13.96 

0.140 

1-533 

1-658 

13-52 

4203.730 

0.172 

i.  880 

2.014 

14-30 

0.164 

1.789 

1.922 

14.09 

0.141 

1-539 

1.664 

13-57 

4207.566 

0.172 

1-875 

2.009 

14.26 

0.164 

1-783 

1.916 

14.06 

0-143 

1.560 

1.685 

13-75 

4216.136 

0.172 

1.870 

2.004 

14.22 

0.163 

1-772 

1.905 

13-97 

0.141 

J-533 

1.658 

13-52 

4220.509 

0.175 

1.900 

2.034 

14-43 

0.164 

1.781 

1.914 

14.04 

0.143 

1-553 

1.678 

13.69 

4232.887 

0.176 

1.902 

2.036 

14-45 

0.165 

1.784 

1.917 

14.06 

0.145 

1.569 

1.694 

13.82 

4233-328 

0.174 

1.881 

2.015 

I4-31 

0.165 

1.784 

1.917 

14.06 

0.146 

1-579 

1.704 

13.90 

4257.815 

0.179 

1.923 

2.057 

14.60 

0.170 

1.827 

1.960 

14-37 

0.146 

1.566 

1.691 

13-79 

4258.477 

0.179 

1.921 

2-055 

14-59 

0.169 

1.814 

1-947 

14.28 

0-145 

1-553 

1.678 

13.69 

4265.418 

0.178 

1.908 

2.042 

14.50 

0.170 

1.824 

1-957 

14-35 

0.146 

1-563 

1.688 

13-77 

4266.081 

0.181 

1.940 

2.074 

14.72 

0.170 

1.822 

1-955 

14-34 

0.146 

1-563 

1.688 

13-77 

4268.915 

0.179 

1-913 

2-047 

14-54 

0.171 

1-825 

1.958 

14.36 

0.146 

1.561 

1.686 

I3-76 

4276.836 

0.179 

1.911 

2.045 

14-53 

0.170 

1.814 

1-947 

14.28 

0.145 

i-SSo 

1-675 

1^.66 

4283.169 

0.180 

1.919 

2-053 

14-57 

0.170 

1.813 

1.946 

14.26 

0.147 

1.569 

1.694 

13-82 

4284.838 

0-179 

1.911 

2.045 

H-S2 

o.i  68 

1.791 

1.924 

14.11 

0.145 

1.546 

1.671 

13-63 

4287.566 

0.181 

1.928 

2.062 

14.64 

0.171 

1.822 

1-955 

14-34 

0.147 

1.568 

1.693 

13.81 

4288.310 

0.179 

1.901 

2-035 

14.46 

0.171 

1.822 

1-955 

14-34 

0.148 

1-577 

1.702 

13.88 

4289.525 

0.178 

1.895 

2.029 

14-39 

0.173 

1-843 

1.976 

14.49 

0.146 

i-SSS 

i.  680 

I3-7I 

4290.377 

0.180 

1.917 

2-051 

I4-S6 

0.170 

1.811 

1-944 

14.26 

0.146 

1-555 

i.  680 

I3-7I 

4290.542 

o.i  80 

1.916 

2.050 

14-54 

0.171 

1.821 

1-954 

14-33 

0.146 

1-554 

1.679 

I3-70 

4291.630 

0.180 

1.916 

2.050 

14-54 

0.172 

1.831 

1.964 

14.40 

0.146 

1-554 

1.679 

I3-70 

0  =  44!S 

0  =  S9°S 

0  =  74!s 

0  =  79!s 

A 

• 

,  +  ,, 

« 

A 

> 

,  +  ,, 

« 

A 

V 

»  +  », 

« 

A 

V 

,+,, 

t 

km 

km 

0 

km 

km 

„ 

km 

km 

0 

km 

km 

0 

4196.699 

O.IO2 

1.116 

1.222 

12.  l6 

0.060 

0.659 

0.740 

10.35 

0.030 

0.329 

0.380 

IO.IO 

0.019 

0.209 

0.249 

9.70 

4197-257 

O.IO2 

1.116 

1.222 

12.  l6 

0.060 

0.659 

0.740 

10.35 

0.029 

0.319 

0.370 

9-83 

0.019 

0.209 

0.249 

9.70 

4203.730 

0.103 

1.124 

1.230 

12.24 

0.062 

0.682 

0.763 

10.67 

0.031 

0.329 

0.380 

IO.IO 

0.019 

0.209 

0.249 

9.70 

4207.566 

0.104 

I-I34 

1.240 

12.34 

0.062 

0.681 

0.762 

10.66 

0.029 

0.319 

0.370 

9-83 

O.O2O 

0.218 

0.258 

10.05 

4216.136 

O.IO4 

1-132 

1.238 

12.32 

0.06  1 

0.669 

0.750 

10.49 

0.029 

0.318 

0.369 

9.80 

0.019 

0.207 

0.247 

9.62 

4220.509 

O.IO4 

1.129 

1-234 

12.28 

0.062 

0.677 

0.758 

10.60 

0.030 

0.329 

0.380 

IO.IO 

O.O2O 

0.217 

0.257 

10.01 

4232-887 

0.106 

1.146 

1.252 

12.46 

0.062 

0.674 

0-755 

10.56 

0-030 

0.326 

0-377 

IO.O2 

O.OI9 

0.206 

0.246 

9-58 

4233-328 

0.105 

I-I35 

I.24I 

12.35 

0.063 

0.684 

0.765 

10.70 

0.030 

0.326 

0-377 

IO.02 

0.020 

0.216 

0.256 

9-97 

4257.8I5 

0.108 

1.161 

1.207 

12.  6l 

0.065 

0.703 

0.784 

10.96 

0.032 

0.346 

0-397 

10-55 

O.O22 

0.236 

0.276 

10-75 

4258.477 

0.106 

1.136 

1.242 

12.36 

0.064 

0.690 

0.771 

10.78 

0.031 

0.336 

0.387 

10.28 

O.Oig 

0.205 

0.245 

9-54 

4265.418 

0.104 

1.115 

1.  221 

12.15 

0.063 

0.679 

0.760 

10.63 

0.032 

0-345 

0.396 

10.52 

O.O2O 

0.215 

0.255 

9-93 

4266.081 

0.107 

1.144 

I.25O 

12.44 

0.065 

0.702 

0-783 

10.97 

0.031 

0-334 

0-385 

10.23 

O.022 

0.235 

0.275 

10.71 

4268.915 

0.108 

I-I54 

1.260 

12.54 

0.066 

0.710 

0.791 

1  1.  06 

0.032 

0-344 

0-395 

10.49 

O.O2I 

0.225 

0.265 

10.32 

4276.836 

o.i  06 

I-I34 

1.240 

12.34 

0.066 

0.708 

0.789 

11.03 

0.032 

0-343 

0-394 

10.47 

O.O2I 

0.225 

0.265 

10.32 

4283.169 

o.i  08 

1.152 

1.258 

12.52 

0.066 

0.707 

0.788 

1  1.  02 

0.031 

0-333 

0.384 

10.20 

O.020 

0.215 

0-255 

9-93 

4284.838 

o.i  06 

1.132 

1.238 

12.32 

0.065 

o.6g6 

0.777 

10.87 

0.031 

0-333 

0.384 

IO.2O 

O.O2I 

0.225 

0.265 

10.32 

4287.566 

0.108 

"1-151 

1-257 

12.51 

0.065 

0.696 

0.777 

10.87 

0.032 

0-343 

0-394 

10.47 

O.O2I 

0.225 

0.265 

10.32 

4288.310 

0.107 

1.140 

1.246 

12.40 

0.064 

0.685 

0.766 

10.71 

0.031 

0-333 

0.384 

10.20 

O.020 

0.215 

0.255 

9-93 

4289.525 

0.106 

1.129 

1-235 

12.29 

0.066 

0.706 

0-787 

1  1.  01 

0.031 

0-333 

0-384 

IO.2O 

O.O22 

0.245 

0.285 

II.  IO 

4290.377 

0.104 

1.107 

I-2I3 

12.07 

0.065 

0.695 

0.776 

10.86 

0.03  1 

0-332 

0-383 

10.  1  8 

O.O2I 

0.225 

0.265 

10.32 

4290.542 

0.104 

1.107 

I.2I3 

12.07 

0.067 

0.716 

0-797 

11.15 

0.032 

0.342 

0-393 

10.44 

O.O2I 

0.225 

0.265 

10.32 

4291.630 

0.103 

1.097 

1.203 

11.97 

0.067 

0.716 

0-797 

11.15 

0.032 

0.342 

0-393 

10-44 

0.022 

0.229 

0.269 

10.48 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1908. 


Plate 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1908  —  Continued. 
136.     1908,  June  n,  sh  4om  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  1.8  mm.    Quality,  good. 


P-P 


seci; 


0.5 

O         80.3 

10.5 

10.5 

79-5 

4.0 

i.  002 

0-12        5.8 

25-5 

25-5 

64-5 

2.7 

1.  000 

P          11.4 

4°-5 

4°-S 

49-5 

1.4 

i.ooo 

D           0.8 

55-5 

55-5 

34-5 

I.O 

I.OOO 

Diameter  167.0  mm 

70.5 

70.5 

19-5 

0.8 

I.OOC 

Factor        1.022 

85-5 

85.5 

4-5 

0.7 

I.OOO 

9°-5 

90-5 

-o-S 

0.7 

I.OOO 

#~* 

*-* 

*-*, 

X 

A 

' 

-.  +  ,, 

« 

A 

' 

.  +  ,, 

* 

A 

V 

,  +  ., 

• 

4196.699 

0.172 

km 
1.882 

km 
2.016 

14-31 

o.i  66 

kin 
.819 

km 
1-953 

13-91 

0-156 

km 

•707 

km 

1.838 

13.84 

4197-257 

0.172 

1.882 

2.016 

I4-3I 

0.167 

.826 

1.960 

13.96 

0.156 

.707 

1-838 

13-84 

4203.730 

0.174 

1.899 

2-033 

14.42 

0.166 

.814 

1.948 

13-87 

0.156 

•703 

1.834 

13.81 

4207.566 

0.174 

1.896 

2.030 

14.40 

0.167 

.821 

1-955 

13.92 

0.158 

•723 

1.854 

13-97 

4216.136 

0.173 

1.882 

2.016 

I4-3I 

0.169 

-839 

1-973 

14.06 

0.157 

•703 

1-834 

13.82 

4220.509 

0-175 

1.896 

2.030 

14.40 

0.171 

•854 

1.988 

14.16 

0.156 

.692 

1.823 

13-73 

4232.887 

0-175 

l-9°3 

2-037 

14.46 

0.171 

-851 

1.985 

14.14 

0.158 

.709 

1.840 

13-86 

4233.328          O.I76 

1.903 

2.037 

14.46 

0-173 

.870 

2.004 

14.27 

0.158 

.709 

1.840 

13.86 

4257-815            o.iSo 

1-935 

2.069 

14.69 

0.174 

.871 

2-005 

14.28 

0.161 

•727 

1.858 

13-99 

4258.477             0.180 

1.932 

2.066 

14.66 

0.176 

.891 

2.025 

14.42 

o.i  60 

•715 

1.846 

13.90 

4265.418 

0.180 

1.930 

2.064 

14.65 

0.174 

-858 

1.992 

14.19 

o.i  60 

.712 

1.843 

13-88 

4266.081 

0.180 

1.927 

2.061 

14-63 

0.174 

.856 

1.990 

14.17 

0.161 

.722 

1-853 

13.96 

4268.915             0.180 

1.924 

2.058 

14.60 

0.175 

-865 

1.999 

14.24 

0-159 

.702 

1.833 

13.81 

4276.836             0.180 

1.922 

2.056 

14-59 

0-173 

•845 

1-979 

14.10 

0.162 

•729 

1.  860 

14.01 

4283.169 

0.179 

1.911 

2.045 

I4-52 

0.172 

•834 

1.968 

14.02 

0.162 

.728 

1.858 

13-99 

4284-838 

0.183 

I-95I 

2.085 

14.80 

0-175 

.864 

1.998 

14-23 

0.161 

.717 

1.848 

13.92 

4287.566 

0.179 

1.908 

2.042 

I4-50 

0.172 

.834 

1.968 

14.02 

0.160 

.707 

1.838 

13-84 

4288.310 

0.180 

.917 

2.051 

I4-56 

0.172 

-832 

1.966 

14.01 

0.163 

•737 

1.868 

14.07 

4289.525 

0.178 

.896 

2.030 

14.40 

0.173 

.844 

1.978 

14.09 

0.162 

.727 

1.858 

13-99 

4290.377 

0.180 

.917 

2.051 

14.56 

0-173 

.844 

1.978 

14.09 

0.162 

•727 

1.858 

13-99 

4290.542 

0.182 

•937 

2.071 

14.70 

0.174 

.852 

1.986 

14-15 

0.162 

.727 

1-858 

13-99 

4291.630 

0.181 

•927 

2.061 

14.63 

0.174 

.852 

1.986 

14-15 

0.163 

•735 

1.864 

14.04 

<f>  =  34?S 

<t>  =  49?S 

*-<«. 

<t>  -  79?S 

X 

A 

V 

.+3 

• 

A 

V 

..Hi 

• 

A 

J) 

,  +  r, 

• 

A 

t) 

.  +  -, 

• 

4196.699 

0.128 

km 

1.400 

km 

I.52C 

0 

13.09 

0.094 

km 

1.028 

km 

.12; 

12.32 

0.052 

km 
1.569 

km 
0.641 

10.57 

O.022 

km 
0.240 

km 

0.280 

O 

10.91 

4197-257 

0.128 

1.400 

I-52C 

13-09 

0.094 

1.028 

.125 

12.32 

0-052 

1.569 

0.641 

10.57 

0.020 

0.220 

0.260 

IO.I2 

4203.730 

0.130 

1.420 

I-S4C 

13-27 

0.098 

1.065 

12.72 

0.052 

I-567 

0.635 

10.54 

O.O2O 

0.219 

0.255 

10.10 

4207.566 

0.130 

1.417 

1-537 

13-24 

O.IOI 

I.IO2 

.201 

13-13 

0-054 

1-590 

0.66; 

10.92 

O.O2I 

0.029 

0.265 

10.48 

4216.136 

0.128 

1.392 

1.515 

13-03 

0.097 

I.O52 

•151 

12.58 

0.051 

1-555 

0.62; 

10.34 

0.020 

0.219 

0.25? 

io.ro 

4220.509 

0.132 

I-43I 

13-36 

0.099 

1.070 

.165 

12.78 

0.054 

1-588 

o.66c 

10.88 

O.O2I 

0.228 

0.268 

10.44 

4232.887 

0.132 

1.428 

1.54? 

13-34 

0.097 

1.048 

.14; 

12.54 

0.054 

1-585 

0.655 

10.83 

O.O2O 

0.218 

0.258 

10.06 

4233.328 

0.132 

1.428 

i-  54^ 

13-34 

0.097 

1.048 

•147 

12.54 

0-053 

1-574 

0.646 

10.65 

0.020 

0.218 

0.258 

10.06 

4257-815 

0.134 

1.440 

i-56c 

13-44 

O.IOO 

1.074 

1.171 

12.82 

0.054 

1.580 

0.652 

10.76 

O.O22 

0.236 

0.276 

10.75 

4258.477 

0-134 

J-439 

1.555 

13-43 

0.098 

I.O52 

1.151 

12.58 

0.054 

1-579 

0.651 

10.74 

O.O2O 

0.216 

0.256 

9-97 

4265.418 

0-134 

1-437 

1-55! 

13-41 

0.099 

I.  O6  1 

i.i6c 

12.68 

0-055 

1.589 

0.661 

10.90 

0.022 

0.236 

0.276 

10.75 

4266.081 

0.134 

1-435 

i-ss: 

13-40 

O.IOI 

I.oSl 

i.iSc 

12.90 

0-054 

1-579 

0.651 

10.74 

O.O22 

0-236 

0.276 

10.75 

4268.915 

0-135 

1.441 

1.561 

13-45 

O.IOO 

I.O7O 

1.165 

12.78 

0-055 

1.589 

0.661 

10.90 

O.O22 

0.236 

0.276 

10.75 

4276.836 

0-135 

1.441 

1.561 

13-45 

O.IOO 

1.  068 

1.16; 

12.76 

0.056 

1-599 

0.671 

11.07 

O.O2O 

0.216 

0.256 

9-97 

4283.169 

0-134 

1.431 

1-551 

13-36 

O.IOO 

1.  066 

.16  = 

12.74 

0.056 

1.596 

11.02 

0.022 

0.236 

0.276 

10-75 

4284.838 

0-135 

1.446 

1-566 

13-49 

0.099 

1-057 

•  156 

12.64 

0-056 

1.596 

o.66f 

1  1.  02 

O.O2O 

0.214 

0.254 

9.90 

4287.566 

0-134 

1-551 

13-36 

0.098 

1.046 

12.52 

0.056 

1-595 

0.66; 

II.OO 

0.021* 

0.225 

0.265 

10.32 

4288.310 

0.136 

1.449 

1-565 

13-52 

O.IOO 

1.065 

12.72 

0-053 

1-564 

0.636 

10.48 

0.022 

0.235 

0.275 

10.71 

4289.525 

0-135 

1.441 

1-561 

13-45 

O.IOO 

1.064 

!i6; 

12.71 

0-055 

1.607 

0.675 

II.  2O 

O.O2I 

0.225 

0.265 

10.32 

4290.377 

0-134 

I-43I 

i-55i 

13-36 

0.099 

1-054 

12.60 

0.056 

1-597 

0.665 

11.04 

O.O2O 

0.214 

0.254 

9.90 

4290.542 

0.136 

1.448 

1-568 

13-51 

0.098 

1.044 

1-145 

12-49 

0.056 

J-597 

0.665 

11.04 

0.020 

0.214 

0.254 

9.90 

4291.630 

0.136 

1.449 

1.565 

13-52 

0.099 

1-053 

1.155 

12-59 

0.058 

1.607 

0.675 

II.  2O 

O.O22 

0.235     0.275 

10.71 

84      AN   INVESTIGATION  OF   THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1908  —  Continued. 
Plate  w  146.     1908,  Aug.  5,  9h  50""  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.3  mm.     Quality,  good. 


P-P 


seer) 


-0-3 

O       133.0 

13.2 

14.6 

7S-4 

2S-3 

.106 

O-Si      58.5 

28.7 

29-3 

60.7 

12.7 

.025 

p      -12.7 

44.2 

44-5 

45-S 

8.8 

.012 

D            6.2 

59-7 

59-9 

30.1 

7.2 

.008 

Diameter  168.6  mm 

74-7 

74.8 

15.2 

6.4 

.006 

Factor        1.016 

89.7 

89.7 

0-3 

6.2 

.O06 

0  = 

ota 

0  = 

** 

0  = 

3* 

A 

tl 

,  +  ,, 

« 

A 

V 

,  +  ,, 

» 

A 

• 

.  +  ,, 

1 

4196.699 

0.171 

km 

1.872 

km 

2.006 

14.24 

0.164 

km 

1.794 

km 

1.926 

14.17 

0-139 

km 
•525 

km 
.646 

13-51 

4197-257 

0.172 

1.881 

2.015 

I4-3I 

0.165 

1.804 

1.936 

14.24 

0.140 

•533 

•654 

13-57 

4203.730 

0.173 

1.887 

2.021 

14-35 

0.166 

1.810 

1.942 

14.29 

0.140 

•530 

.651 

13-55 

4207.566 

0.170 

1.854 

1.988 

14.11 

0.165 

1.798 

1.930 

14.20 

0.142 

•551 

.672 

13.72 

4216.136 

0.172 

1.870 

2.004 

I4-23 

0.165 

1-794 

1.926 

14.17 

0.141 

•535 

.656 

13-59 

4220.509 

0-173 

1.879 

2.013 

14.29 

o.i  66 

.802 

1-934 

14-23 

0.140 

•523 

.644 

13-49 

4232-887 

0.176 

1.904 

2.038 

14.47 

0.167 

-805 

•937 

14-25 

0.141 

•529 

•  650 

13-54 

4233-328 

0.177 

1.914 

2.048 

14-54 

0.167 

.805 

•937 

14-25 

0.142 

•538 

•659 

13.61 

4257-815 

0.178 

I-9I3 

2.047 

14-53 

0.169 

-815 

•947 

14-32 

0.144 

•546 

.667 

13.68 

4258.477 

0.177 

1.902 

2.036 

14-45 

0.167 

.791 

•923 

14-15 

0.143 

-536 

.657 

13.60 

4265.418 

0.178 

1.901 

2-035 

14-45 

0.168 

.800 

•932 

14.21 

0.143 

-536 

.657 

13.60 

4266.081 

0.179 

1.918 

2.052 

14-57 

0.170 

.819 

•951 

14-35 

0.143 

-536 

•657 

13.60 

4268.915 

0.180 

1.927 

2.061 

14-63 

0.168 

•799 

.931 

14.21 

0.143 

•535 

.656 

13-59 

4276.836 

0.178 

1.898 

2.032 

14.42 

0.168 

•794 

.926 

14.17 

0.144 

•538 

-659 

13.61 

4283-169 

0.178 

1.897 

2.031 

14.42 

0.170 

.812 

•944 

14-30 

0.144 

•538 

•659 

13.61 

4284.838 

0.179 

1.907 

2.O4I 

14.49 

0.168 

•792 

•924 

14-15 

0.143 

•527 

1.648 

I3-52 

4287.566 

0.177 

1.886 

2.020 

14.34 

0.170 

.812 

1.944 

14-30 

0.143 

-526 

1.647 

I3-52 

4288.310 

0.178 

1.895 

2.029 

14.40 

o.i  68 

•790 

1.922 

14.14 

0.147 

•570 

1.691 

13.88 

4289-525 

0.177 

1.885 

2.OI9 

14.33 

0.170 

.810 

1.942 

14.29 

0-143 

-530 

1.651 

13-55 

4290.37? 

0.178 

1.896 

2.030 

14.41 

0.171 

.820 

1-952 

14-36 

0-143 

-528 

1.649 

13-53 

4290.542 

0.179 

1.905 

2.039 

14.48 

0.169 

.798 

1.930 

14.20 

0.144 

•537 

1.658 

13-61 

4291-630 

0.178 

1.894 

2.028 

14.40 

o.i  68 

.790 

1.922 

14.14 

0.146 

•557 

1.678 

13-77 

0  = 

«*, 

0  = 

6°!? 

0  = 

7St4 

4196.699 

0.105 

I-I55 

1.256 

12.72 

0.059 

0.652 

0.725 

10.53 

0.028 

0-337 

0-377 

10.62 

4197-257 

0.105 

i-iSS 

1.256 

12.72 

0.059 

0.652 

0-725 

10.53 

0.030 

0.361 

0.401 

11.29 

4203-730 

o.i  06 

1.163 

1.264 

1  2.  80 

0.063 

0.698 

0.771 

1  1.  20 

0.032 

0.382 

0.422 

11.88 

4207.566 

o.i  06 

1.162 

1.263 

12-79 

0.062 

0.685 

0.758 

II.OI 

0.030 

0.360 

0.400 

11.27 

4216.136 

0.106 

1.156 

1-257 

12.73 

0.062 

0.683 

0.756 

10.98 

0.029 

0.348 

0.388 

10.93 

4220.509 

0.106 

i-iS5 

1.256 

12.72 

0.062 

0.683 

0-756 

10.98 

0.030 

0-358 

0.398 

II.  21 

4232-887 

0.106 

1-254 

12.70 

0.062 

0.683 

0.756 

10.98 

0.031 

0.369 

0.409 

11-52 

4233.328 

0.108 

•175 

1.276 

12.92 

0.064 

0.705 

0.778 

11.30 

0.030 

0-357 

0-397 

ii.  18 

4257-815 

0.108 

.168 

1.269 

12.85 

0.064 

0.701 

0.774 

11.24 

0.032 

0.376 

0.416 

11.72 

4258.477 

0.109 

.174 

1-275 

12.91 

0.064 

0.698 

0.771 

ii.  20 

0.031 

0.365 

0.405 

11.41 

4265.418 

0.107 

•153 

1.254 

12.70 

0.064 

0.698 

0.771 

ii.  20 

0.032 

0.376 

0.416 

11.72 

4266.081 

O.IIO 

.186 

1.287 

13.04 

0.063 

0.688 

0.761 

11.05 

0.031 

0-365 

0.405 

11.41 

4268.915 

0.109 

.172 

1.273 

12.89 

0.064 

0.695 

0.768 

11.15 

0,032 

0-375 

0.415 

11.69 

4276.836 

0.107 

.150 

1.251 

12.67 

0.064 

0.695 

0.768 

11.15 

0.030 

0.352 

0.392 

11.04 

4283.169 

0.108 

•159 

1.260 

12.76 

0.063 

0.684 

0-757 

10.99 

0.031 

0.364 

0.404 

11-38 

4284.838 

0.108 

.158 

1-259 

12.75 

0.062 

0.675 

0.748 

10.86 

0.033 

0.386 

0.426 

12.00 

4287.566 

0.108 

•157 

1.258 

12.74 

0.062 

0.675 

0.748 

10.86 

0.031 

0-363 

0.403 

"•35 

4288.310 

O.IIO 

.178 

1.279 

12.95 

0.064 

0.694 

0.767 

11.14 

0.032 

0-375 

0-415 

11.69 

4289.525 

0.108 

.170 

1.271 

12.87 

0.062 

0.674 

0.747 

10.85 

0.031 

0.363 

0.403 

"•35 

4290.377 

0.109 

.179 

1.280 

12.96 

0.06  1 

0.663 

0.736 

10.69 

0.030 

0-352 

0.392 

11.04 

4290.542 

0.108 

.168 

1.269 

12.85 

0.063 

0.683 

0.756 

10.98 

0-033 

0.386 

0.426 

12.  OO 

4291-630 

0.108 

1.167 

1.268 

12.84 

0.060 

0.651 

0.724 

10.51 

0.030 

0.392 

11.04 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1908. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  <»  147.     1908,  Aug.  5,  ioh  30™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.5  mm.     Quality,  good. 


P-f 


seci 


-0.3 

0 

i33-o 

13.2 

14.6 

754 

25-3 

1.106 

O-n 

S8.S 

28.7 

29-3 

60.7 

12.7 

1.025 

p 

-12.7 

44.2 

44-5 

45-S 

8.8 

I.OI2 

D 

6.2 

59-7 

59-9 

30.1 

7.2 

1.008 

Diameter 

168.6  mm 

74-7 

74.8 

15-2 

6.4 

1.  006 

Factor 

1.018 

89.7 

89.7 

0-3 

6.2 

I.  OO6 

<t>  = 

°°3 

0  = 

is!* 

0  = 

3°!i 

A 

V 

"»  +  »! 

£ 

A 

r 

fl  +  »l 

£ 

A 

V 

11  +  11l 

{ 

4196.699 

0.174 

km 

I-905 

km 
2.039 

14.48 

0.164 

km 

1.796 

km 
1.928 

14.18 

O.H3 

km 

1.568 

km 
1.689 

13-86 

4I97-257 

0.174 

I-905 

2.039 

14.48 

0.165 

1.  806 

1.938 

14.26 

0.143 

.568 

1.689 

13.86 

4203.730 

0.075 

1.912 

2.046 

H-53 

0.167 

1-825 

1-957 

14.40 

0.144 

•578 

1.699 

13-94 

4207.566 

0.176 

I.92I 

2-055 

M-59 

0.168 

1.833 

1.965 

14.46 

0.144 

•574 

1.695 

13-91 

4216.136 

0-175 

I-905 

2.039 

14.48 

o.i  66 

1.807 

1-939 

14.26 

0.143 

•554 

I.675 

13-75 

4220.509 

0.176 

I-9H 

2.048 

14-54 

o.i  68 

1.827 

1-959 

14.41 

0.145 

•574 

1.695 

I3-9I 

4232.887 

0.177 

I-9I7 

2.051 

14.56 

0.168 

1.820 

1.952 

14.36 

0-145 

•573 

1.694 

13.90 

4233-328 

0.178 

1.927 

2.061 

14.63 

0.168 

.819 

I-95I 

14-35 

0.144 

•562 

1.683 

13.81 

4257-8I5 

0.179 

1-925 

2.059 

14.62 

0.170 

.828 

1.960 

14.42 

0.146 

•570 

1.691 

13.88 

4258.477 

0.178 

I-9H 

2.048 

14-54 

0.170 

.828 

1.960 

14.42 

0.146 

i-57o 

1.691 

13-88 

4265.418 

0.179 

1.922 

2.056 

14.60 

0.173 

.856 

1.988 

14.62 

0.146 

1.569 

1.690 

13-87 

4266.081 

0.180 

I-93I 

2.065 

14.06 

0.170 

.825 

1-957 

14.40 

0.144 

1-542 

1.663 

13-65 

4268.915 

0.178 

1.908 

2.042 

14.50 

0.170 

.823 

1-955 

14.38 

0.148 

-583 

1.704 

13.98 

4276.836 

0.179 

1.916 

2.050 

14-55 

0.171 

.826 

1.958 

14.40 

0.146 

-562 

1.683 

13.81 

4283.169 

0.180 

1.921 

2-055 

14-59 

0.171 

.826 

1.958 

14.40 

0.145 

•551 

1.672 

I3-72 

4284.838 

0.180 

1.920 

2.054 

14.58 

0-173 

.847 

J-979 

14.56 

0.146 

.565 

1.686 

13.84 

4287.566 

0.181 

1-930 

2.064 

14.65 

0.172 

.835 

1.967 

14.47 

0.146 

-564 

1.685 

I3-83 

4288.310 

0.180 

1.919 

2-053 

14.58 

0-173 

.846 

1.978 

14-55 

0.145 

•554 

1-675 

13-74 

4289.525 

0.181 

1.929 

2.063 

14.65 

0.174 

.856 

1.988 

14.63 

0.148 

.581 

1.702 

13-97 

4290.377 

0.180 

1.919 

2-053 

14.58 

0.170 

.812 

1-944 

14-30 

0.146 

•562 

1.683 

13-81 

4290.542 

0.180 

1.918 

2-052 

14-57 

0.171 

.822 

1-954 

14.38 

0.145 

•552 

1-673 

13-73 

4291.630 

0.180 

1.918 

2-052 

14-57 

0.172 

1.832 

1.964 

14-45 

0.148 

.580 

1.701 

13.96 

0  = 

4s!s 

0  = 

6o!7 

<t>  = 

7S?4 

4196.699 

O.IO2 

-132 

1-233 

12.49 

0.062 

0.689 

0.762 

11.07 

0.029 

0-349 

0.389 

10.96 

4I97-257 

O.IO4 

-145 

1.246 

12.62 

0.062 

0.689 

0.762 

11.07 

0.030 

0.358 

0.398 

II.  21 

4203.730 

0.106 

.164 

1.265 

12.81 

0.063 

0.698 

0.771 

n.  20 

0.030 

0-357 

0-397 

ii.  18 

4207.566 

0.106 

.163 

1.264 

12.80 

0.063 

0.698 

0.771 

11.20 

0.030 

0-357 

0-397 

ii.  18 

4216.136 

0.107 

.171 

1.272 

12.88 

0.063 

0.697 

0.770 

II.I8 

0.029 

0-347 

0.387 

10.90 

4220.509 

0.106 

•157 

1.258 

12.74 

0.063 

0.697 

0.770 

ii.  18 

0.032 

0-379 

0.419 

11.80 

4232-887 

0.106 

.156 

1-257 

12-73 

0.063 

0.697 

0.770 

11.18 

0.030 

0-354 

0-394 

II.  IO 

4233-328 

0.108 

.176 

1-277 

12.93 

0.066 

0.727 

0.800 

11.62 

0.030 

0-354 

0-394 

II.  IO 

4257-8I5 

0.109 

.179 

1.280 

12.96 

0.066 

0.719 

0.792 

11.50 

0.032 

0.370 

0.410 

"•55 

4258.477 

O.IIO 

.189 

1.  200 

13-07 

0.066 

0.719 

0.792 

11.50 

0.032 

0.370 

0.410 

"•55 

4265.418 

0.108 

.162 

1.263 

12.79 

0.066 

0.719 

0.792 

11.50 

0.032 

0.370 

0.410 

"•55 

4266.081 

0.108 

.162 

1.263 

12.79 

0.065 

0.706 

0.779 

11.31 

0.030 

o.35o 

0-390 

10.98 

4268.915 

0.109 

•171 

1.272 

12.88 

0.065 

0.706 

0-779 

11.31 

0.030 

0-350 

0.390 

10.98 

4276.836 

O.I  OQ 

.171 

1.272 

12.88 

0.066 

0.715 

0.788 

11.44 

0.031 

0.360 

0.400 

11.27 

4283.169 

0.108 

.160 

1.261 

12.77 

0.065 

0.705 

0.778 

11.30 

0.032 

0.370 

0.410 

"•55 

4284.838 

O.I  I  I 

.192 

1.293 

13.10 

0.066 

0.715 

0.788 

11.44 

0.032 

0-370 

0.410 

"•55 

4287.566 

0.108 

-163 

1.264 

12.80 

0.068 

0.738 

0.811 

11.78 

0.032 

0.370 

0.410 

"•55 

4288.310 

O.IIO 

.182 

1-283 

13.00 

0.067 

0.728 

0.801 

11.63 

0.030 

0.350 

0.300 

10.98 

4289.525 

O.III 

.191 

1.292 

13.09 

0.065 

0.705 

0.778 

11.30 

0.032 

0.370 

0.410 

"•55 

4290.377 

0.109 

.169 

1.270 

12.86 

0.064 

0.695 

0.768 

11.15 

0.031 

0.360 

0.400 

11.27 

4290.542 

0.109 

.169 

1.270 

12.86 

0.065 

0.704 

0.777 

11.28 

0.030 

0.350 

0-390 

10.98 

4291.630 

O.IIO 

.179 

1.280 

12.96 

0.065 

0.704 

o-777 

11.28 

0.033 

0.385 

0-425 

11.97 

86      AN  INVESTIGATION  OF   THE  ROTATION  PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


Plate 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
148.     1908,  Aug.  5,  ioh  30™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.4  mm.     Quality,  good. 

v  p  —  P  ""  0  *7 


-0.3 

O       133.0 

13.2 

14.6 

75-4 

2S-3 

.106 

0-0      58.5 

28.7 

29-3 

60.7 

12.7 

.025 

p     -12.7 

44-2 

44-5 

45  -S 

8.8 

.012 

1   D          6.2 

59-7 

59-9 

30.1 

7.2 

.008 

Diameter  168.6  mm 

74-7 

74.8 

15-2 

6.4 

.006 

Factor        i  .01  7 

89.7 

89.7 

0-3 

6.2 

.OO6 

0=o?3 

*-*. 

0  =  3o!i 

A 

V 

.  +  „ 

« 

A 

• 

,-M, 

£ 

A 

•a 

,-M, 

* 

4196.699 

0.173 

km 
1.896 

km 

2.030 

0 

14.41 

o.i  66 

km 
1.817 

km 
1-949 

14-34 

0.142 

km 
1-558 

km 

1.679 

o 

13-78 

4197.257 

0-175 

1.916 

2.050 

14-55 

0.165 

1.807 

1-939 

14.26 

0.143 

1.568 

1.689 

13.86 

4203.730 

0.174 

1.903 

2.037 

14.46 

o.i  66 

1.811 

1-943 

14.29 

0.144 

1-576 

1.697 

13-93 

4207.566 

0.176 

1.921 

2-055 

14-59 

0.167 

1.821 

1-953 

14-37 

0.146 

1-597 

1.718 

14.10 

4216.136 

0.176 

I-9I3 

2.047 

14-53 

0.167 

1.818 

1.950 

14-35 

0.144 

i-57o 

1.691 

13.88 

4220.509 

0.178 

1.936 

2.070 

14.70 

0.169 

1-831 

1.963 

14.44 

0-145 

1-579 

1.700 

13-95 

4232.887 

0.176 

1.911 

2.045 

I4-52 

0.167 

1.811 

1-943 

14.29 

0-145 

1-573 

1.694 

13.90 

4233.328 

0.178 

1.927 

2.061 

14.64 

0.170 

1.841 

1-973 

14-52 

0.144 

1.562 

1.683 

13.81 

4257.815 

0.178 

I-9I5 

2.049 

14-55 

0.170 

1.827 

1-959 

14.41 

0.146 

1-574 

1.695 

13-91 

4258.477 

0.178 

I-9I4 

2.048 

14-54 

0.168 

1.807 

1-939 

14.26 

0.147 

1-583 

1.704 

13.98 

4265.418 

0.180 

.929 

2.063 

14-65 

0.170 

1.824 

1.956 

14-39 

0.145 

1.560 

i.  68  1 

13-79 

4266.081 

0.180 

.928 

2.062 

14.64 

0.170 

1.824 

1.956 

14-39 

0.146 

1.569 

1.690 

13-87 

4268.915 

0.178 

.908 

2.042 

I4-50 

0.172 

1.842 

1-974 

14-52 

0.146 

1-563 

1.684 

13.82 

4276.836 

o.i75 

-873 

2.007 

14.27 

0.172 

1.841 

1-973 

14.52 

0-147 

1-573 

1.694 

13.90 

4283.169 

0.181 

•935 

2.069 

14.69 

0.170 

1.815 

1-947 

14-33 

0.146 

1.562 

1.683 

13.81 

4284.838 

0.182 

•945 

2.079 

14-76 

0.170 

1-815 

1-947 

14-33 

0.146 

1.561 

1.682 

13.80 

4287.566 

0.182 

•943 

2.077 

14-75 

0.173 

1.849 

1.981 

14-57 

0.144 

1.540 

1.661 

13-63 

4288.310 

0.181 

•931 

2-065 

14.66 

0.172 

1-837 

1.969 

14.49 

O.I4S 

1-550 

1.671 

i3-7i 

4289.525 

0.182 

.941 

2.075 

14-73 

0.172 

1.836 

1.968 

14.48 

0.147 

1-570 

1.691 

13.88 

4290.377 

0.181 

•929 

2.063 

14.65 

0.172 

1-835 

1.967 

14.47 

0.147 

1-570 

1.691 

13.88 

4290.542 

0.182 

•939 

2.073 

14.72 

0.174 

1-853 

1.985 

14.60 

0.146 

1-559 

i.  680 

13-78 

4291.630 

0.182 

•939 

2.073 

14.72 

0.172 

1-833 

1.965 

14.46 

0.146 

1-559 

i.  680 

I3-78 

0  =  4S!S 

0  =  6o°7 

0  =  rs!4 

4196.699 

0.107 

1.177 

1.278 

12.94 

0.064 

0-713 

0.786 

11.41 

0.029 

0.348 

0.388 

10.93 

4197.257 

0.105 

i-i57 

1.258 

12.74 

0.064 

0-713 

0.786 

11.41 

0.030 

0-358 

0.398 

II.  21 

4203.730 

0.106 

1.165 

1.266 

12.82 

0.067 

0-733 

0.806 

11.70 

0.030 

0-358 

0.398 

II.  21 

4207.566 

0.107 

1.174 

1-275 

12.91 

0.065 

0.721 

0-794 

11-53 

0.031  !    0.368 

0.408 

11.49 

4216.136 

0.106 

1.158 

1.259 

12-75 

0.064 

0.710 

0.783 

ii-37 

0.030  '    0.356 

0-396 

11.15 

4220.509 

0.108 

1.177 

.278 

12.94 

0.066 

0.730 

0.803 

11.66 

0.031 

0.366 

0.406 

H-43 

4232.887 

0.107 

1.165 

.266 

12.82 

0.068 

0.738 

0.811 

11.78 

0.031 

0.366 

0.406 

II  -43 

4233.328 

0.107 

1.165 

.266 

12.82 

0.065 

0.716 

0.789 

11.46 

0.032 

0.376 

0.416 

11.72 

4257-815 

0.107 

I-I53 

•254 

12.70 

0.068 

0-733 

0.806 

11.70 

0.031 

0.361 

0.401 

11.29 

4258.477 

0.108 

1.163 

.264 

12.80 

0.068 

0-732 

0.805 

11.69 

0.032 

o-37i 

0.411 

11-58 

4265.418 

0.107 

1.153 

•254 

12.70 

0.068 

0-731 

0.804 

11.67 

0.031 

0.361 

0.401 

11.29 

4266.081 

0.108 

.163 

.264 

12.80 

0.066 

0.720 

0-793 

11.52 

0.031 

0.361 

0.401 

11.29 

4268.915 

0.107 

•151 

-252 

12.68 

0.068 

0.728 

0.801 

11.63 

0.032 

0-371 

0.411 

11.58 

4276.836 

0.108 

.161 

.262 

12.78 

0.068 

0.728 

0.801 

11.63 

0.032 

0.371 

0.411 

11-58 

4283.169 

O.IIO 

.181 

.282 

12.98 

0.069 

0.738 

0.811 

11.78 

0.031 

0.361 

0.401 

11.29 

4284.838 

0.108 

•159 

.260 

12.76 

0.067 

0.718 

0.791 

11.49 

0.032 

0.360 

0.400 

11.27 

4287.566 

0.107 

.149 

.250 

12.66 

0.068 

0.728 

0.801 

11.63 

0.030 

0-350 

0.390 

10.98 

4288.310 

0.108 

.161 

.262 

12.78 

0.067 

0.727 

0.800 

11.62 

0.032 

0-370 

0.410 

"-5S 

4289.525 

O.IIO 

.181 

1.282 

12.98 

0.068 

0.726 

0.799 

1  1.  60 

0.031 

0.360 

0.400 

11.27 

4290.377 

0.108 

.160 

1.261 

12.77 

0.066 

0.718 

0.791 

n-49 

0.032 

0.370 

0.410 

ii-5S 

4290.542 

O.IIO 

.179 

1.280 

12.96 

0.067 

0.726 

0.799 

1  1.  60 

0.032 

0.370 

0.410 

"•55 

4291.630 

0.108 

.158 

1-259 

12.75 

0.067 

0.726 

0-799 

11.60 

0.031 

0.360 

0.400 

11.27 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS    OF    1908. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  151.     1908,  Aug.  6,  sh  15™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.5  mm.     Quality,  good. 


P-P 


'I' 


secij 


o-3 

0       133-8 

13-8 

iS-i 

74-9 

24.6 

1.  100 

o-n     59-3 

29.6 

30.2 

59-8 

12-5 

1.024 

p     -13.1 

45-i 

45-4 

44.6 

8.8 

1.012 

D           6.3 

75-3 

75-4 

14.6 

6.4 

1.  006 

Diameter  168.6  mm 

9°-3 

9°-3 

-0-3 

6.2 

I.  OO6 

Factor        1.018 

<t-  = 

-  °°3 

*- 

-  o°3 

•t>  = 

i4?6 

A 

» 

V  +  V1 

J 

A 

V 

V  -fllj 

J 

A 

V 

»  +  »! 

1 

km 

km 

« 

km 

km 

- 

km 

km 

0 

4196.699 

0.174 

1.908 

2.042 

14.50 

0-173 

1.899 

2-033 

14-43 

0.163 

1.788 

1.920 

14.09 

4I97-2S7 

O.I7S 

1.918 

2.052 

14-57 

0-175 

1.918 

2.052 

14-57 

0.164 

1.797 

1.929 

I4-IS 

4203.730 

0.177 

1.936 

2.070 

14.70 

0.178 

1.936 

2.070 

14.70 

0.166 

1.815 

1-947 

14.28 

4207.566 

0.176 

.918 

2.052 

H-57 

0.177 

1.928 

2.062 

14.64 

0.165 

1.803 

1-935 

14.20 

4216.136 

0.176 

•915 

2.049 

14-55 

0.175 

I-905 

2.039 

14-47 

0.165 

1.799 

I-93I 

14.17 

4220.509 

0.176 

.911 

2.045 

14-52 

0.177 

1.921 

2.055 

14.60 

0.167 

1.813 

1-945 

14.28 

4232.887 

0.180 

•949 

2.083 

14.79 

0.176 

1.908 

2.042 

14.50 

0.168 

I.82I 

1-953 

14-32 

4233-328 

0.177 

.918 

2.052 

M-57 

0.177 

1.918 

2.052 

14-57 

o.i  68 

I.82I 

1-953 

14.32 

4257-8I5 

0.180 

•937 

2.071 

14.71 

0.180 

1-937 

2.071 

14.71 

0.169 

1.819 

i-95i 

I4-31 

4258.477 

0.182 

•959 

2.093 

14.86 

0.179 

1.928 

2.062 

14.64 

o.i  68 

1.809 

1.941 

14.24 

4265.418 

0.179 

•923 

2.057 

14.61 

0.180 

1-933 

0.067 

14.68 

0.170 

1.827 

1-959 

14.38 

4266.081 

O.I  80 

•932 

2.066 

14.67 

0.179 

1.922 

2.056 

14.61 

0.170 

1.826 

1.958 

14-37 

4268.915 

0.180 

•93° 

2.064 

14.66 

0.180 

1.930 

2.064 

14-65 

0.171 

1.829 

1.961 

14-39 

4276.836 

0.180 

.928 

2.062 

14.64 

0.180 

1.928 

2.062 

14.64 

0.171 

1.828 

1.960 

14-38 

4283.169 

0.181 

•933 

2.067 

14.68 

0.179 

I-9I3 

2.047 

14-54 

0.170 

1.818 

1.950 

14.30 

4284.838 

0.181 

•933 

2.067 

14.68 

0.181 

1-933 

2.067 

14.68 

0.172 

1.838 

1.970 

14-45 

4287.566 

0.180 

.922 

2.056 

14.60 

0.181 

1.932 

2.066 

14.67 

0.170 

1.818 

1.950 

14.30 

4288.310 

0.179 

.912 

2.046 

H-53 

0.181 

1-932 

2.066 

14.67 

0.172 

1-837 

1.969 

14.44 

4289.525 

0.182 

1.942 

2.076 

14.74 

0.182 

1.942 

2.076 

14.74 

0.171 

1.827 

1-959 

14-37 

4290.377 

O.I  80 

1.921 

2.055 

14-59 

0.181 

I-93I 

2.065 

14.66 

0.171 

1.827 

1-959 

14-37 

4290.542 

0.182 

1.942 

2.076 

14-74 

0.181 

1.932 

2.066 

14.67 

0.173 

1.845 

1.977 

14.50 

4291.630 

0.181 

I-93I 

2.065 

14.66 

0.182 

1.941 

2.075 

14-73 

0.172 

1-835 

1.967 

H-43 

<t>  = 

44!6 

0  = 

sots 

0  = 

74!9 

4196.699 

0.105 

•159 

.260 

12.56 

0.065 

0.724 

0.797 

11.25 

0.029 

0.348 

0.388 

10.57 

4I97-257 

0.105 

.158 

•259 

12.55 

0.064 

0.714 

0.787 

II.  II 

0.030 

0.358 

0.398 

10.85 

4203.730 

0.106 

.164 

.265 

12.  6l 

0.066 

0-734 

0.807 

"•39 

0.030 

0-357 

0-397 

10.82 

4207.566 

0.106 

.162 

.263 

12-59 

0.067 

0-745 

0.818 

"•55 

0.031 

0.368 

0.4,08 

II.  12 

4216.136 

0.104 

.140 

.241 

12.37 

0.066 

0.732 

0.805 

11.36 

0.031 

0.367 

0.407 

II.O9 

422O.5O9 

0.106 

•159 

.260 

12.56 

0.066 

0.732 

0.805 

11.36 

0.030 

0-357 

0-397 

10.82 

4232.887 

0.108 

.178 

.279 

12.75 

0.067 

0-739 

0.812 

11.46 

0.031 

0-365 

0.405 

11.03 

4233-328 

0.108 

.178 

.279 

12.75 

0.068 

0-749 

0.822 

1  1.  60 

0.031 

0-365 

0.405 

11.03 

4257-8I5 

0.109 

•177 

.278 

12.74 

0.069 

0-753 

0.826 

11.66 

0.033 

0.388 

0.428 

11.66 

4258.477 

0.108 

.166 

1.267 

12.63 

0.067 

0-733 

0.806 

11.38 

0.032 

0.376 

0.416 

"•34 

4265.418 

0.108 

.164 

1.265 

12.61 

0.064 

0.702 

0-775 

10.94 

0.032 

0.376 

0.416 

"•34 

4266.O8I 

0.109 

•174 

1-275 

12.71 

0.065 

0.711 

0.784 

1  1.  06 

0.032 

0-374 

0.414 

11.28 

4268.9J5 

0.108 

.164 

1.265 

12.61 

0.069 

0.750 

0.823 

11.61 

0.032 

0-374 

0.414 

11.28 

4276.836 

0.109 

.172 

1-273 

12.69 

0.068 

0-739 

0.812 

11.46 

0.032 

0-374 

0.414 

11.28 

4283.169 

O.IIO 

.182 

1.283 

12.79 

0.068 

0-739 

0.812 

11.46 

0.033 

0.384 

0.424 

"•55 

4284.838 

0.109 

.171 

1.272 

12.68 

0.068 

0-739 

0.812 

11.46 

0.034 

0.396 

0.436 

11.88 

4287.566 

O.IIO 

.181 

1.282 

12.78 

0.069 

0-749 

0.822 

1  1.  60 

0.034 

0.396 

0-436 

11.88 

4288.3IO 

0.108 

.161 

1.262 

12.58 

0.066 

0.718 

0.791 

ii.  16 

0.032 

0.374 

0.414 

11.28 

4289.525 

0.109 

.170 

1.271 

12.67 

0.068 

0-739 

0.812 

11.46 

0.032 

0-374 

0.414 

11.28 

4290.377 

0.109 

1.170 

1.271 

12.67 

0.068 

0-739 

0.812 

11.46 

0-033 

0.385 

0.425 

11.58 

4290.542 

O.IIO 

1.180 

1.281 

12.77 

0.068 

0-739 

0.812 

11.46 

0.033 

0.396 

0.436 

11.88 

4291.630 

O.IIO 

1.180 

1.281 

12.77 

0.071 

0.771 

0.844 

n-75 

0.034 

0.396 

0.436 

11.88 

88      AN  INVESTIGATION   OF  THE  ROTATION  PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1908  —  Continued. 
Plate  w  161.     1908,  Aug.  26,  nh  om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  i.i  mm.     Quality,  good. 


P-P 


secy 


-0-3 

0       153-3 

24.1 

25.0 

65.0 

17.0 

1.049 

o-n     78.8 

40.1 

40.6 

49.4 

II.  0 

1.018 

p     -19.8 

SS'S 

55-8 

34.2 

8.6 

1.016 

D           7.1 

70.7 

70.9 

19.1 

7-5 

1.009 

Diameter  168.9  mm 

79.0 

79.1 

10.9 

7.2 

1.008 

Factor        1.013 

83.8 

85.8 

4.2 

7-i 

1.008 

0  = 

4!  2 

<t>  = 

IO°Q 

0  = 

I9?i 

A 

V 

v  +  vt 

i 

A 

V 

v  +  v1 

i 

A 

V 

»  +  »! 

i 

4196.699 

0.172 

km 

1.879 

km 

2.015 

14-34 

o.i  68 

km 

1.836 

km 
1.970 

14.24 

0.159 

km 
1-739 

km 
1.867 

o 

14.04 

4197-25? 

0.1/3 

1.888 

2.024 

14.41 

o.i  68 

1.836 

1.970 

14.24 

0.159 

1-739 

1.867 

14.04 

4203.730 

0.175 

1-913 

2.049 

14-59 

0.169 

1.840 

1.974 

14.27 

0.162 

1.766 

1.890 

14.21 

4207.566 

0-175 

1.910 

2.046 

14.56 

o.i  68 

1.828 

1.962 

14.19 

0.161 

1-753 

I.88I 

14.14 

4216.136 

O.I7S 

1.908 

2.044 

14-55 

o.i  68 

1.826 

1.960 

14.17 

0.161 

1-75' 

1.879 

14.13 

4220.509 

0.176 

1.905 

2.041 

14-53 

0.172 

1.867 

2.001 

14.47 

0.163 

.766 

!.894 

14.24 

4232.887 

0.176 

1.902 

2-038 

14-51 

0-173 

1.869 

2.003 

14.49 

0.164 

•774 

1.902 

14.30 

4233-328 

0.176 

1.902 

2.038 

14-51 

0.172 

1.859 

1-993 

14.42 

0.165 

.784 

1.912 

14.37 

4257-815 

0.179 

1.920 

2.056 

14.63 

0.176 

1.884 

2.018 

14.59 

0.163 

•744 

1.872 

14.08 

4258-477 

0.178 

1.910 

2.046 

14.56 

0.174 

1.864 

1.998 

14-45 

0.164 

•753 

i.  88  1 

14.14 

4265.418 

0.179 

1.918 

2.054 

14.62 

0.172 

1.842 

1.976 

14.29 

0.164 

•753 

1.881 

14.14 

4266.081 

0.179 

1.917 

2-053 

14.61 

O.I7S 

1.867 

2.OOI 

14.47 

0.167 

1-783 

1.911 

14.36 

4268.915 

0.180 

1.926 

2.062 

14.68 

0.174 

1.856 

1.990 

14-39 

0.166 

1.772 

1.900 

14.28 

4276.836 

0.176 

1.878 

2.014 

14-34 

0.174 

1-855 

1.989 

14.38 

0.164 

I-75I 

1.879 

14.13 

4283.169 

0.180 

1.918 

2.054 

14.62 

0.175 

1.865 

1.999 

14.46 

0.167 

.781 

1.909 

14.35 

4284.838 

0.180 

1.916 

2.052 

14.61 

0.174 

I.8S5 

1.989 

14.38 

0.165 

.760 

1.888 

14.19 

4287.566 

0.180 

1.916 

2.052 

14.61 

0.175 

1.864 

1.998 

14-45 

0.165 

.760 

1.888 

14.19 

4288.310 

0.179 

1.906 

2.042 

14-54 

0-175 

1.864 

1.998 

14-45 

0.165 

.760 

1.888 

14.19 

4289-525 

0.179 

1.906 

2.042 

14-54 

0.174 

1-854 

1.988 

14.38 

0.162 

.725 

1-853 

13.93 

4290.377 

0.179 

1.905 

2.041 

14-53 

0.174 

1.854 

1.988 

14.38 

0.162 

•725 

1-853 

13.93 

4290.542 

0.180 

1-915 

2.051 

14.60 

0.174 

1-853 

1.987 

14.37 

0.164 

•747 

1-875 

14.10 

4291.630 

0.180 

1-915 

2.051 

14.60 

0.176 

1.873 

2.OO6 

14.51 

o.i  66 

.768 

1.896 

14.25 

<t>  = 

34?2 

0  = 

49°A 

0  = 

65!° 

4196.699 

0.128 

1.404 

I-5I9 

13-03 

0.088 

0.972 

1.061 

11.57 

0.048 

0.541 

0-599 

10.06 

4197-25? 

0.128 

1.404 

I-5I9 

13-03 

0.088 

0.972 

1.  06  1 

"•57 

0.048 

0.541 

0-599 

10.06 

4203  730 

0.128 

1.412 

-528 

13.12 

0.090 

0.992 

1.081 

11.79 

0.049 

0-551 

0.609 

10.23 

4207.566 

0.131 

1.430 

•545 

13-25 

0.090 

o  990 

1079 

11.77 

0.050 

0.561 

0.619 

10.40 

4216.136 

0.132 

1.438 

•553 

13-32 

0.090 

0.988 

1.077 

"•75 

0.047 

0-530 

0.588 

9.88 

4220.509 

0.131 

1.426 

•541 

13.22 

0.092 

1.005 

1.094 

"•93 

0.050 

0-559 

0.617 

10.37 

4232.887 

0.132 

1-434 

•549 

13.29 

0.091 

0.994 

1.083 

11.81 

0.051 

0.569 

0.627 

10.54 

4233.328 

0.132 

I-43I 

•546 

13.26 

0.090 

0.984 

1-073 

11.70 

0.051 

0.569 

0.627 

10.54 

4257-815 

0-135 

1.450 

-565 

13-43 

0.092 

0.996 

1.085 

11.83 

0.054 

0-599 

0.657 

11.04 

4258.477 

0-135 

1.450 

•565 

13-43 

0.092 

0.996 

1.085 

11-83 

0.054 

0.598 

0.656 

n.  02 

4265.418 

o-i33 

1.429 

•544 

13-24 

0.090 

0-974 

1.063 

n-59 

0-053 

0.588 

0.646 

10.85 

4266.081 

0-135 

1-445 

.560 

13-38 

0.092 

0.992 

1.081 

11-79 

0.052 

0-575 

0-633 

10.63 

4268.915 

0-135 

•445 

•560 

13-38 

0.093 

1.  002 

1.091 

11.90 

0-053 

0-585 

0.643 

10.80 

4276.836 

0-133 

•424 

•539 

13.20 

0.092 

0.992 

1.081 

11.79 

0.053 

0.585 

0.643 

10.80 

4283.169 

0-134 

•435 

•550 

13-30 

0.092 

0.992 

1.081 

11.79 

0.052 

0-575 

0.633 

10.63 

4284.838 

0.134 

•435 

•550 

13-30 

0.090 

0.972 

1.  06  1 

n-57 

0.052 

0.576 

0.634 

10.65 

4287.566 

0.134 

-435 

•550 

13-30 

0.092 

0.991 

1.080 

11.78 

0-053 

0.586 

0.644 

10.82 

4288.310 

0.136 

•451 

-566 

13-43 

0.093 

1.  001 

1.090 

11.89 

0.053 

0.586 

0.644 

10.82 

4289.525 

0-133 

.421 

-536 

13.18 

0.092 

0.991 

1.080 

11.78 

0.051 

0-565 

0.623 

10.47 

4290.377 

0-135 

.441 

-556 

13-35 

0.091 

0.981 

1.070 

11.67 

0.052 

0-575 

0.633 

10.63 

4290.542 

0.135 

1.441 

-556 

13-35 

0.093 

1.  001 

1.090 

11.89 

0.054 

0-595 

0-653 

10.97 

4291.630 

0.133 

1.420 

•535 

13-17 

0.095 

1.  02  1 

I.  IIO 

12.  II 

0.054 

0-595 

0-653 

10.97 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1908. 


8g 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  162.     1908,  Aug.  26,  ii1'  om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  i.i  mm.     Quality,  good. 


P-P 


seer] 


-0.3 

0       153-3 

24.1 

25.0 

65.0 

17.0 

1.046 

O-n     78.8 

40.1 

40.6 

49.4 

II.O 

1.019 

P      -19.8 

55-5 

55-8 

34-2 

8.6 

1.  01  1 

D            7.1 

70.7 

70.9 

19.1 

7-5 

1.009 

Diameter  168.9  mm 

79.0 

79.1 

10.9 

7.2 

1.  008 

Factor        1.013 

85.8 

85.8 

4.2 

7-i 

1.008 

0  =  4!* 

0  =  io°9 

0  =  IQ!I 

. 

A 

' 

.  +  ., 

s* 

A 

V 

»  +  », 

• 

A 

V 

.  +  ,, 

« 

4196.699 

0.174 

km 

1.901 

km 
2.037 

i4°5o 

o.i  68 

km 
1.838 

km 
1.972 

I4.2S 

0.157 

km 
1.719 

km 

1.847 

13.88 

4197-257 

0.174         i.  ooi 

2.037 

14-50 

o.i  68         1.838 

1.972 

I4.25 

0.158 

1.728 

.856 

13-95 

4203.730 

0.175 

1.909 

2.045 

14.56 

0.170           .853 

1.987 

14.36 

o.i  60 

1-743 

.871 

14.06 

4207.566 

0.176 

.914 

2.050 

14-59 

0.169  i        .841 

1-975 

14.27 

0.161 

I-75I 

.879 

I4-I3 

4216.136 

0.175 

.901 

2-037 

14.50 

0.170           .848 

.982 

I4.32 

0-159 

1.729 

-857 

13-97 

4220.509 

0.177 

.917 

2.053 

14.61 

0.170           .845           .979 

14.30 

0.162 

1-755 

.883 

14.16 

4232-887 

0.178 

.924 

2.060 

14.66 

0.170 

.840 

•974 

14.26 

0.161 

1-743 

.871 

14.07 

4233-328 

0.180 

•944 

2.080 

14.80 

0.173 

.870 

.004 

14.48 

0.164 

1-773 

.901 

14.29 

4257-SiS 

0.179 

.921 

2-057 

14.64 

0.172 

.848 

.982 

I4-32 

0.165 

1.766 

•894 

14.25 

4258-47? 

0.178 

.910 

2.046 

14.56 

0-173 

-857 

.991 

14-39 

0.164 

1-754 

.882 

M-iS 

4265.418 

0.179 

•915 

2.051 

H-59 

0.173 

•854 

.988 

14-37 

0.163 

1.742 

.870 

14.06 

4266.081 

0.179 

.914 

2.050 

14-59 

0-175 

.874 

.008 

14.52 

0.164 

J-752 

.880 

14-13 

4268.915 

0.180 

.919 

2.055 

14.63 

0.174 

.856 

.990 

14.38 

0.164 

.879 

14.12 

4276.836 

0.181 

.928 

2.064 

14.69 

0.174 

-855 

.989 

14-37 

0.164 

1-749 

-877 

14.11 

4283.169 

0.178 

.897 

2.033 

14.47 

o.i74 

-854 

.988 

14-37 

0.165 

1-759 

.887 

14.19 

4284.838 

0.180 

1.914 

2.050 

14-59 

0.173 

.842 

.976 

14.28 

0.164 

1-747 

-875 

14.10 

4287.566 

0.180 

I-9I3 

2.049 

14.58 

0.174 

-852 

.986 

14-35 

.  0.163 

1-737 

.865 

14.02 

4288.310 

0.180 

I-9I3 

2.049 

14.58 

0.174 

-8SI 

•985 

14-34 

0.164 

1-747 

•875 

14.10 

4289.525 

0.180 

I-9I3 

2.049 

14.58 

0.175 

.861 

J-995 

14.41 

0.164 

1-747 

-875 

14.10 

4290.377 

0.178 

1.893 

2.029 

14.44 

0.174 

.851 

1.985 

14-34 

0.164 

1-747 

-875 

14.10 

4290.542 

0.178 

1.893 

2.029 

14.44 

0.176 

.872 

2.006 

14.50 

0.165 

I-756 

.884 

14.17 

4291.630 

0.179 

1.903 

2.039 

14-51 

0.175 

.862 

1.996 

14-43 

0.165 

I-756 

.884 

14.17 

0  =  34^ 

0  =  49°A 

0  —  6s!o 

0  =  6s!o* 

, 

A 

» 

,-M, 

• 

A 

V 

»  +  r 

« 

A 

r 

.  +  J      « 

A 

p 

v  +  1>1 

« 

4196-699 

0.125 

km 

I-37I 

km 

.486 

12.76 

0.095 

km 
1.049 

km 
.138 

12.42 

0.057 

km 

0.646 

km 

0.704      11.83 

0.050 

km 
0.569 

km 
0.62; 

10.53 

4197-257 

0.125 

I-37I 

.486 

12.76 

0.095 

1.049 

.138 

12.42 

0.058 

0.656 

0.714 

I2.OO 

0-053 

0.603 

0.661 

II.  IO 

4203.73° 

0.126 

1.381 

.496 

12.84 

0.097 

1.068 

•157 

12.62 

0.058 

0.655 

0.713 

Il.gS 

0-055 

0.625 

0.683 

11.47 

4207.566 

0.126 

1-377 

•492 

I2.8l 

0.094 

1-035 

.124 

12.26 

0.056 

0-635 

0.693 

11.64 

0.050 

0.567 

0.62! 

10.50 

4216.136 

0.126 

1-374 

.489 

12.78 

0.096 

1-053 

.142 

12.46 

0.059 

0.660 

0.718 

I  2.06 

0.050 

0-565 

0.623 

10.47 

4220.509 

0.129 

1.405 

.520 

13-05 

0.097 

1.  060 

.149 

12.53 

0.057 

0.640 

0.698 

"•73 

0.057 

0.643 

0.701 

11.78 

4232.887 

0.127 

1-379 

•494 

12.82 

0.097 

1-058 

-147 

12.51 

0.058 

0.649 

0.70; 

11.87 

0.056 

0.630 

o.688|    11.56 

4233.328 

0.129 

1-399 

•SM 

12.99 

0.096 

1.048 

•137 

12.40 

0.058 

0.649 

0.705 

11.87 

0.052 

0.585 

0.643 

10.80 

4257-815 

0.130 

1.400 

•515 

13.00 

0.098 

1.063 

•152 

12.57 

0.058 

0.645 

0.703 

ii.  81 

0.057 

0.637 

o.6gt 

11.68 

4258.477 

0.129 

1.390 

•505 

12.92 

0.098 

1.063 

•152 

12-57 

0-059 

0.655 

0.713 

11.98 

0.057 

0.636 

0.69; 

11.66 

4265.418 

0.129 

1.389 

•504 

12.91 

0.097 

1.047 

.136 

12-39 

0.058 

0.643 

0.701 

11.78 

0-053 

0.590 

0.648 

10.88 

4266.081 

0.131 

1.408 

•523 

13.07 

0.098 

1-057 

.146 

12.50 

0.058 

0.643 

0.701 

11.78 

0.054 

0.580 

0.638 

10.72 

4268.915 

0.130 

1-394 

•509 

12-95 

0.098 

1.056 

•145 

12.49 

0.060 

0.664 

0.722 

12.13 

0.057 

0-635 

0.693 

11.64 

4276.836 

0.130 

1.390 

•505 

12.92 

0.098 

1-055 

.144 

12.48 

0.059 

0.651 

0.70? 

11.91 

0-055 

0.6  1  1 

o.66<; 

11.24 

4283.169 

0.131 

.400 

•515 

13.00 

0.099 

1.065 

-154 

12-59 

0.060 

0.661 

0.71? 

12.08 

0.060 

0.665 

0.723 

11.15 

4284.838 

0.130 

•390 

•505 

12.92 

0.099 

1.064 

•153 

12.58 

0.061 

0.650 

0.708 

11.89 

0.055 

0.609 

0.66; 

1  1.  20 

4287.566 

0.130 

•390 

•505 

12.92 

0.097 

1.044 

•133 

12.36 

0.058 

0.640 

0.698 

"•73 

0.057 

0.630 

0.688 

11.56 

4288.310 

0.131 

•399 

.514 

12.99 

0.098 

1-053 

.142 

12.46 

0.06  1 

0.670 

0.728 

12.23 

0.058 

0.642 

0.700 

11.76 

4289.525 

0.131 

•399 

•514 

12.99 

0.099 

1.063 

•152 

12.57 

0.060 

0.660 

0.718 

12.06 

0.06  1 

0.675 

0-733 

12.31 

4290-377 

0.129 

•379 

1.494 

12.82 

0.097 

1.043 

.132 

12.35 

0.058 

0.640 

0.698     11.73 

0.057 

0.632 

o.6ox 

"-S9 

4290.542 

0.132 

.409 

I-524 

13.08 

0.099 

1.063 

•152 

12-57 

0.060    0.660    0.718     12.06 

0.060 

0.665 

0.723 

12.15 

4291.630 

0.129 

.378     1.493 

12.82 

0.098     1.053 

1.142      12.46 

0.060    0.660    0.718     12.06 

0.058 

0-655 

0-713 

11.98 

*  Measured  by  A.  on  G. 


go      AN  INVESTIGATION   OF  THE  ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC  METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  163.     1908,  Aug.  26,  nh  55m  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  i.i  mm.     Quality,  good. 


p-P 


sec  i) 


-0-3 

o 

153-3 

24.1 

25.0 

65.0 

17.0 

1.046 

o-n 

78.8 

40.1 

40.6 

494 

II.O 

1.019 

p 

-19.8 

ss-s 

55-8 

34-2 

8.6 

I.  Oil 

D 

7-i 

70.7 

70.9 

19.1 

7-5 

1.009 

Diameter 

168.9  mm 

79.0 

79.1 

10.9 

7.2 

1.008 

Factor 

1.013 

85.8 

85-8 

4.2 

7-i 

1.008 

*  =  * 

0   =   IO°Q 

0  -  „:, 

A 

n 

,  +  ,, 

« 

A 

V 

"  +  "j 

« 

A 

V 

v  +  »t 

« 

4196.699 

0.172 

km 

1.880 

km 
2.0l6 

14-34 

0.170 

km 
1.859 

km 
1-993 

o 

14.40 

O.I  60 

km 
•750 

km 

1.878 

14.12 

4197-257 

0.172 

.880 

2.016 

14-34 

0.170  1       1.859 

1-993 

14.40 

0.160 

•750 

1.878 

14.12 

4203.730 

0.173 

.889 

2.025 

14.42 

0.173          1-887 

2.O2I 

14.60 

0.162 

.768 

1.896 

14-25 

4207.566 

0.173 

.885 

2.O2I 

14.38 

0.172 

1.874 

2.008 

14-51 

0.162 

.765 

1.893 

14-23 

4216.136 

0.174 

.890 

2.O26 

14.42 

0.170 

1.849 

1.983 

14-33 

0.162 

.762 

1.890 

14.21 

4220.509 

0.177 

.922 

2-058 

1465 

0.174 

1.888 

2.022 

14.61 

0.163 

.765 

1.893 

14.23 

4232.887 

0.177 

.911 

2.047 

14-57 

0.172 

1.859 

1-993 

14.40 

0.164 

•773 

1.901 

14.29 

4233-328 

0.176 

.901 

2.037 

14.50 

0.174 

i.  880 

2.014 

14-55 

0.164 

•773 

1.901 

14.29 

4257-8i5 

0.178 

.910 

2.046 

14-56 

0-175 

1.879 

2.013 

14-54 

0.166 

.782 

1.910 

14.36 

4258-477 

0.178 

.910 

2.046 

14.56 

0.174 

1.869 

2.003 

14-47 

0.165 

•773 

1.901 

14.29 

4265.418 

0.178 

.909 

2-045 

14.56 

0.176 

1.884 

2.018 

14.58 

0.162 

•738 

1.866 

14-03 

4266.081 

0.179 

•915 

2.051 

14.60 

0-175 

1.874 

2.008 

14-51 

0.165 

.762 

1.890 

14.21 

4268.915 

0.178 

1.904 

2.040 

14-52 

0-175 

1.867 

2.OOI 

14.46 

0.165 

.761 

1.889 

14.20 

4276.836 

0.180 

1.917 

2-053 

14.61 

0.175 

1-865 

1-999 

14-45 

0.164 

•750 

1.878 

14.12 

4283.169 

0.178 

1.896 

2.032 

14-47 

0.175 

1.865 

1-999 

14-45 

0.164 

•750 

1.878 

14.12 

4284.838 

0.180 

•915 

2.051 

14.60 

0.176 

1.874 

2.008 

14-51 

0.164 

.748 

1.876 

14.10 

4287.566 

0.179 

•905 

2.O4I 

14-53 

0.175 

1.864 

1.998 

14-44 

0.165 

•758 

1.886 

14.18 

4288.310 

0.178 

•895 

2.031 

14.46 

0.175 

1.864 

1.998 

14.44 

0.164 

.748 

1.876 

14.10 

4289.525 

O.I  80 

•915 

2.051 

14.60 

0.174 

1-853 

1.987 

14.36 

0.165 

•758 

1.886 

14.18 

4290.377 

0.179 

•90S 

2.041 

14-53 

0.175 

1.863 

1.997 

14-43 

0.164 

.748 

1.876 

14.10 

4290.542 

0.180 

.914 

2.050 

14-59 

O.I7S 

1.863 

1.997 

14-43 

0.165 

•758 

1.886 

14.18 

4291.630 

0.180 

1.914 

2.050 

14-59 

0.174 

1.852 

1.986 

14-35 

0.164 

•  747 

1-875 

14.09 

0  =  34^ 

0  =  49?4 

0  =  6s!o 

0=6SV 

X 

A 

i) 

,-M, 

£ 

A 

' 

.  +  ., 

« 

A 

* 

.  +  ., 

« 

A 

» 

,  +  ,, 

I 

4196.699 

0.131 

km 
.441 

km 
1-556 

13-36 

0.094 

km 

1.038 

km 

1.127 

12.30 

0.056 

km 
0.634 

km 

0.692 

11-63 

0.050 

km 

0.569 

km 

0.627 

o 

10.53 

4197-257 

0.130 

•430 

1-545 

13.26 

0.094 

1.038 

1.127 

12.30 

0.056 

0.634 

0.692!    11.63 

0.052!    0.592 

0.650 

10.92 

4203-730 

0.132 

•443 

1-558 

13-37 

0.096 

1.058 

1.147 

12.52 

0.057 

0.643 

0.701 

11.78 

0.054!    0.612 

0.670 

11.26 

4207.566 

0.132 

.440 

1-555 

13-35 

0.096 

1.056 

I-I45 

12.49 

0.057 

0.642 

0.700 

11.76 

0.052 

0.589 

0.647 

10.87 

4216.136 

0.131 

.429 

1-544 

13-25 

0.095 

1.044 

I-I33 

12.36 

0.056 

0.630 

0.688 

11.56 

0.052 

0.588 

0.646 

10.85 

4220.509 

0.132 

•437 

1-552 

13-32 

0.096 

1.052 

1.141 

12.45 

0.059 

0.663 

0.721 

12.  II 

0.058 

0.654 

0.712 

11.96 

4232.887 

0.132 

•435 

1-550 

13-30 

0.099 

1.081 

1.170 

12.77 

0.058 

0.650 

0.70$ 

11.89 

0.055 

0.618 

0.676 

11.36 

4233.328 

0-133 

.442 

1-557 

13-36 

0.098 

1.070 

•159 

12.65 

0.058     0.650 

0.708 

11.89 

0.052 

0-585 

0.643 

1080 

4257-815 

0-133 

•433 

1.548 

13.29 

0.099 

1.074 

.163 

12.69 

0.060 

0.666 

0.724 

12.  l6 

0-055 

0.615 

0.673 

11.31 

4258-477 

0.133 

•433 

1.548 

13.29 

0.098 

1.064 

•153 

12.58 

0.0581    0.646 

0.704 

11-83 

0.054 

0.605 

0-633 

11.14 

4265.418 

0.134 

•435 

i-55o 

13-30 

0.096 

1.042 

•131 

12.34 

0.060    0.666 

0.724 

12.  l6 

0.056 

0.624 

0.682 

11.46 

4266.081 

0-134 

•435 

i-55o 

13-30 

0.098 

1.057 

.146 

12.50 

0.059 

0-653 

0.711 

11.94 

0-055 

0.614 

0.672 

11.29 

4268.915 

0.135 

•444 

1-559 

13-38 

0.098 

1.056 

•145 

12.49 

0.059 

0.652 

0.7  ic 

11.92 

0.056 

0.623 

0.681 

11.44 

4276.836 

0.134 

•433 

1.548 

13.29 

0.099 

1.065 

•154 

12.59 

0.060 

0.659 

0.717 

12.04 

0-055 

0.613 

0.671 

11.27 

4283.169 

0.132 

.412 

1-527 

13.10 

0.099 

1.065 

•154 

12-59 

0.058 

0.639 

0.697 

11.71 

0.057 

0.631 

0.689 

ii-57 

4284.838 

0.134 

•433 

1.548 

13.29 

0.098 

1.054 

•143 

12.47 

0.060 

0.659 

0.717 

12.04 

0.054 

0-599 

0.657 

11.04 

4287.566 

0.134 

•433 

1.548 

13.29 

0.100 

1-075 

1.164 

12.70 

0.059 

0.649 

0.707 

11.88 

0.055  1    0.609 

0.667 

it.  20 

4288.310 

0.134 

•432 

1-547 

13.28 

o.ioi 

1.085 

1.174 

12.81 

0.060 

0.659 

0.717 

12.04 

0.056 

0.619 

0.677 

"•37 

4289.525 

0.134 

•431 

1.546 

13-27 

0.099 

1.064 

I-I53 

12.58 

0.058 

0.639 

0.697 

11.71 

0.056 

0.619 

0.677 

"•37 

4290.37? 

0.133 

.420 

1-535 

13.18 

0.098 

1-053 

1.142 

12.46 

0.058 

0.639 

0.697 

11.71 

0.054 

0.598 

0.656 

1  1.  02 

4290.542 

0.134 

I-43I 

1.546 

13-27 

O.IOI 

1.085 

1.174 

12.81 

0.060 

0.659 

0.717 

12.04 

0.056     0.619 

0.677 

n-37 

4291.630 

0.134 

I-43I 

1.546     13.27 

0.098 

1-053 

1.142 

12.46 

0.059    0.649 

0.707     11.88 

0.057 

0.630 

0.688 

11.56 

*  Measured  by  A.  on  G. 


RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    igo8. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  164.     1908,  Aug.  26,  nh  55m  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  i.i  mm.     Quality,  good. 


P-P 


scc>7 


-o-3 

0       1S3-3 

24.1 

25.0 

65.0 

17.0 

1.046 

o-n     78.8 

40.1 

40.6 

49.4 

II.O 

1.019 

p     -19.8 

55-5 

55-8 

34-2 

8.6 

I.  Oil 

D           7.1 

70.7 

70.9 

19.1 

7-S 

1.009 

Diameter  168.9  mm 

79.0 

79.1 

10.9 

7.2 

1.008 

Factor        1.013 

85.8 

85.8 

4.2 

7-i 

1.008 

0  = 

4!  2 

0= 

u*, 

0  = 

10:1 

X 

A 

V 

,  +  „ 

i. 

A 

V 

„+„ 

« 

A 

' 

,  +  ., 

« 

^196.699 

0.169 

km 

.848 

km 

1.984 

14.12 

0.169 

km 

1.858 

km 
1.992 

14.40 

0.159 

km 
•739 

km 

1.867 

14.04 

4197-257 

0.171 

.868 

2.004 

14.26 

0.168 

1.848 

1.982 

14-32 

0-159 

•739 

1.867 

14.04 

4203.730 

0-173 

.885 

2.O2I 

14.38 

0.170 

1.853 

.987 

14-36 

o.t6i 

•752 

1.880 

14-13 

4207.566 

0.174 

.894 

2.030 

14-45 

0.171 

i.  860 

•994 

14.41 

O.I  60 

•741 

1.869 

14-05 

4216.136 

0.174 

.890 

2.O26 

14.42 

0.170 

1.848 

.982 

14.32 

0.159 

.729 

1.857 

13-97 

4220.509 

0.177 

1.920 

2.056 

14.64 

0.173 

1.872 

.006 

14-50 

0.162 

•754 

1.882 

14-15 

4232-887 

0.176 

1.901 

2-037 

14.50 

0.172 

•859 

•993 

14.41 

0.162 

•752 

1.880 

14-13 

4233-328 

0.176 

1.900 

.      2.036 

14.49 

0.172 

.859 

•993 

14.41 

o.i  60 

•730 

1.858 

13.98 

4257.8i5 

0.178 

1.898 

2-034 

14.48 

0.174 

.867 

2.OOI 

14.46 

0.162 

.741 

1.869 

14-05 

4258.477 

0.178 

1.898 

2.034 

14.48 

0-174 

.867 

2.001 

14.46 

0.163 

•751 

1.879 

14.12 

4265.418 

0.177 

1.895 

2.031 

14.46 

0-175 

•874 

2.008 

14.51 

0.161 

.726 

1.854 

13-94 

4266.081 

0.179 

•915 

2.051 

14.60 

O.I7S 

.874 

2.008 

14-51 

0.163 

.742 

1.870 

14.06 

4268.915 

0.178 

.898 

2.034 

14.48 

0.174 

.861 

1-995 

14.42 

0.163 

.741 

1.  869 

14.05 

4276.836 

0.177 

.886 

2.O22 

14-39 

0.174 

•859 

1-993 

14.40 

0-163 

•739 

1.867 

14.04 

4283.169 

0.178 

.896 

2.032 

14.46 

0.175 

.863 

1-997 

14.44 

0.164 

•749 

1.877 

14.11 

4284.838 

0.179 

•904 

2.040 

14-52 

0.174 

•853 

1.987 

14.36 

0.162 

.727 

1.855 

13-95 

4287.566 

0.178 

.894 

2.030 

14-45 

o.i75 

.862 

1.996 

14-43 

0.162 

.726 

1.854 

13-94 

4288.310 

0.177 

.884 

2.O2O 

14-37 

0.174 

.852 

1.986 

14-35 

0.165 

•757 

1.885 

14.17 

4289.525 

0.178 

•893 

2.029 

14.44 

0.176 

.872 

2.006 

14.50 

0.164 

•747 

I.875 

14.10 

4290.377 

0.178 

1.893 

2.O29 

14.44 

0.174 

.852 

1.986 

14-35 

0.164 

•747 

I.875 

14.10 

4200.542 

0.178 

1.893 

2.O29 

14.44 

0.176 

.872 

2.006 

14.50 

0.164 

•747 

1.875 

14.10 

4291.630 

0.179 

1.903 

2.039 

14-51 

0.174 

1.852 

1.986 

14-35 

0.165 

•756 

1.884 

14.16 

0  = 

34!2 

0  = 

4*4 

0  = 

65:o 

4196-699 

0.130 

.425 

1.540 

13.22 

0.096 

1-059 

.148 

12-53 

0.055 

0.624 

0.682 

11.46 

4197-257 

0.130 

•425 

1-540 

13.22 

0.096 

1.059 

.148 

12.53 

0.057 

0.644 

0.702 

11-79 

4203-730 

0-133 

•455 

1-570 

13.48 

0.097 

1.064 

•153 

12.58 

0.058 

0.654 

0.712 

11.96 

4207.566 

0.133 

•454 

1.569 

13-47 

0.097 

1.062 

•151 

12.56 

0.057 

0.644 

0.702 

11.79 

4216.136 

0.131 

.426 

I-S4I 

13-23 

0.096 

1.050 

•139 

12.43 

0.056 

0.630 

0.688 

11.56 

4220.509 

0.132 

•434 

1-549 

13-30 

0.097 

1.  060 

.149 

12-54 

0.058 

0.649 

0.707 

11.88 

4232.887 

0.133 

.441 

I-556 

13-36 

0.096 

1.048 

•137 

12.40 

0.057 

0.638 

0.696 

11.69 

4233-328 

0.133 

.441 

I-556 

13-36 

0.099 

1.081 

.170 

12.76 

0.058 

0.648 

0.706 

11.86 

42  C7  8l  < 

O.I36 

460 

j      ~-  - 

I3-52 

t^o  /  •"*  J 

OT  7  A 

•t"" 

I  .CCA 

4265.418 

•  l  OT" 

0.135 

•449 

1.564 

13-43 

0.099 

1.072 

.161 

12.66 

0.058 

0.643 

0.701 

11.77 

4266.O8I 

0.134 

•436 

i-SSi 

I3-3I 

0.098 

.063 

•152 

12.57 

0.058 

0.642 

0.700 

n-75 

4268.915 

0.135 

•444 

•559 

13-38 

0.099 

.071 

.160 

12.65 

0.058 

0.639 

0.697 

11.71 

4276.836 

0-135 

•444 

•559 

13-38 

O.IOO 

.077 

.166 

12.61 

0.059 

0.649 

0.707 

11.88 

4283.169 

0.134 

•432 

•547 

13.28 

0.100 

•077 

.166 

12.61 

0.058 

0.639 

0.697 

11.71 

4284.838 

0.134 

•432 

•547 

13.28 

0.098 

•056 

•145 

12-49 

0.059 

0.648 

0.706 

11.86 

4287.566 

0-133 

•431 

•546 

13-27 

0.098 

-055 

.144 

12.48 

0.058 

0.638 

0.696 

11.69 

4288.3IO 

0.136 

•453 

.568 

13-46 

0.098 

1-055 

.144 

12.48 

0.058 

0.638 

0.696 

11.69 

4289.525 

0-135 

.442 

1-557 

13-36 

0.099 

1.065 

•154 

12.59 

0.059 

0.648 

0.706 

11.86 

4290.377 

O.I3S 

1.442 

1-557 

13-36 

0.097 

1.044 

•133 

12.36 

0.059 

0.648 

0.706 

11.86 

4290.542 

0.137 

1.462 

1-577 

13-54 

O.IOO 

1.074 

.163 

12.69 

0.059 

0.648 

0.706 

11.86 

4291.630 

0.135 

1.441 

I-S56 

13-35 

O.IOO 

1.074 

.163 

12.60 

0.058 

0.638 

0.696 

11.69 

92      AN  INVESTIGATION   OF   THE   ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC   METHODS. 


TABLE  u. — RESULTS  FOE  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  165.     1908,  Aug.  27,  6h  45™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.6  mm.     Quality,  good. 


P-P 


sec'; 


—  O.2 

O       154.1 

24.2 

25.2 

64.8 

17.0 

1.046 

O-fi      79.6 

40.1 

40.6 

49.4 

II.O 

1.019 

P          -20.1 

55-6 

55-9 

34-1 

8.6 

1.  01  1 

D           7.1 

70.8 

70.9 

19.1 

7o 

1.009 

Diameter  168.8  mm 

78.3 

78.4 

u.6 

7-3 

1.008 

Factor        1.019 

85.8 

85.8 

4.2 

7-i 

1.008 

0  =4% 

0  =  n°6 

*-* 

A 

It 

»  +  », 

« 

A 

V 

.  +  * 

« 

A 

V 

1 

4196.699 

0.169 

km 
1.861 

km 

1.997 

14.22 

0.169 

km 

1.858 

km 

1.992 

14-43 

0.158 

km 

1-738 

km 

1.867 

14.03 

4197-257 

0.169 

1.861 

1.997 

14.22 

o.i  68 

1.848 

1.982 

14.36 

0.157 

I.736 

1.865 

14.01 

4203.730 

0.172 

1.887 

2.023 

14.40 

0.170 

1.864 

1.998 

14.48 

o.i  60 

I-756 

1.885 

14.16 

4207.566 

0.173 

1.898 

2.034 

14.48 

0.170 

1.863 

1.997 

14.47 

o.i  60 

1-752 

1.881 

14-13 

4216.136 

0-173 

•883 

2.019 

14-37 

0.171 

1.868 

2.002 

14-52 

o.i  60 

1-750 

1.879 

14.11 

4220.509 

0.176 

.923 

2.059 

14.66 

0.170 

1.852 

1.986 

14.40 

0.161 

1-759 

1.888 

14.19 

4232.887 

0.175 

•90S 

2.041 

14-53 

0.172 

1.870 

2.OO4 

M-53 

0.161 

1-763 

1.892 

14.22 

4233-328 

0.176 

•915 

2-051 

14.60 

0.171 

1.  860 

1.994 

14-43 

0.162 

1.762 

1.891 

14.21 

4257-815 

0.178 

.922 

2.058 

14.65 

0.173 

1.870 

2.004 

14-53 

0.163 

1.761 

1.890 

14.20 

4258-47? 

0.175 

.891 

2.027 

14-43 

0.173 

1.869 

2.003 

14.52 

0.163 

1.761 

1.890 

14.20 

4265.418 

0.176 

.896 

2.032 

14.47 

0.172 

1.854 

1.988 

14.41 

0.163 

1-758 

1.887 

14.18 

4266.081 

0.176 

-895 

2.031 

14.46 

0.173 

1-857 

I-99I 

14-43 

0.162 

1.748 

•877 

14.10 

4268.915             0.178 

.916 

2-052 

14.61 

0.174 

1.866 

2.OOO 

14.50 

0.163 

I-756 

-885 

14.16 

4276.836 

0.176 

.892 

2.028 

14.44 

0-173 

I-8SS 

1.989 

14.42 

0.162 

1-739 

.868 

14.04 

4283.169 

0.178 

.907 

2-043 

14-54 

0.174 

1.865 

1.999 

14.49 

0.163 

1.748 

-877 

14.10 

4284.838 

0.176 

.886 

2.  02  2 

14.40 

0.174 

1.864 

1.998 

14.48 

0.162 

i  737 

.866 

14.02 

4287-566 

0.177 

.898 

2.034 

14.48 

0.172 

1.844 

1.978 

14-34 

0.164 

1-757 

.886 

14.17 

4288.310 

0.176 

-885 

2.O2I 

14-39 

0.172 

1.843 

1.977 

14-33 

0.163 

1-747 

.876 

14.09 

4289.525 

0.178 

•905 

2.O4I 

14-53 

0.174 

1.864 

1.998 

14.48 

0.163 

1-747 

.876 

14.09 

4290.37? 

0.176 

.884 

2.020 

14-38 

0.173 

1.851 

1.985 

14-39 

0.163 

J-747 

1.876 

14.09 

4290.542 

0.177 

.894 

2.030 

14-45 

0.172 

1.841 

J-975 

14-31 

0.164 

1-757 

1.886 

14.17 

4291-630 

0.178 

•90S 

2.O4I 

14-53 

0.173 

1.851 

1.985 

14-39 

0.163 

1-747 

1.876 

14.09 

0  =  34?i 

0  -  49?4 

0  =  64!8 

4196.699 

0.131 

1.444 

-558 

13-36 

0.095 

•°54 

•143 

12.47 

0.054 

0.611 

0.669 

11.15 

4197-257 

0.130 

i  -434 

•548 

13.27 

0.094 

.044 

•'33 

12.36 

0.054 

0.611 

0.669 

11.15 

4203.730 

0.131 

1-443 

•557 

13-35 

0.094 

.042 

•131 

12.34 

0-055 

0.632 

0.690 

11.51 

4207.566 

0-133 

1.462 

•576 

13-51 

0.095 

•054 

•143 

12.37 

0-055 

0.620 

0.678 

11.31 

4216.136 

0.132 

1.446 

.560 

13-37 

0.094 

•039 

.128 

12.31 

0-055 

0.618 

0.676 

11.27 

4220.509 

0.134 

.467 

.581 

J3-47 

0.097 

.068 

•157 

12.62 

0.057 

0.636 

0.694 

"•57 

4232.887 

0.132 

.441 

•555 

13-33 

0.096 

•054 

•143 

12.37 

0.056 

0.625 

0.683 

4233-328 

0.131 

•431 

•545 

13-25 

0.096 

•054 

•143 

12.37 

0.058 

0.645 

0.703 

"•73 

4257-815 

0.133 

•443 

•557 

13-35 

0.097 

.058 

.147 

12.51 

0.057 

0.628 

0.686 

11.44 

4258.477 

0.134 

•453 

.567 

13-44 

0.098 

.068 

•157 

12.62 

0.057 

0.628 

0.686 

11.44 

4265.418 

0.134 

•438 

•552 

13-30 

0.097 

•052 

.141 

12.45 

0.058 

0.637 

0.695 

"•59 

4266.081 

0.132 

.428 

•542 

13.22 

0.098 

.062 

•151 

12.56 

0.058 

0-637 

0.695 

"•59 

4268.915 

0-133 

1.438 

•552 

13-30 

0.097 

.052 

.141 

12.45 

0.058 

0-637 

0.695 

"•59 

4276.836 

0.134 

1-443 

•557 

13-35 

0.096 

.041 

-130 

12.33 

0.057 

0.627 

0.685 

11.42 

4283.169 

0-134 

1.441 

•555 

13-33 

0.096 

.041 

.130 

12.33 

0.057 

0.627 

0.685 

11.42 

4284.838 

0.133 

1.430 

-544 

13-24 

0.097 

.050 

•139 

12-43 

0.058 

0.636 

0.694 

"•57 

4287.566 

0.134 

1.440 

-554 

13-32 

0.098 

.060 

.149 

12-54 

0.057 

0.626 

0.684 

11.40 

4288.310 

0.135 

1.450 

-564 

13-41 

0.098 

.060 

1.149 

12.54 

0.058 

0.636 

0.694 

"•57 

4289.525 

0.135 

1.450 

•564 

13-41 

0.097 

1.050 

I-I39 

12-43 

0-059 

0.646 

0.704 

"•75 

4290-377 

0.135 

1.449 

-563 

13.40 

0.098 

1.059 

1.148 

12-53 

0.058 

0.636 

0.694 

"•57 

4290.542 

0.134 

1-439 

•553 

13-31 

0.097 

1.049 

1.138 

12.43 

0.058 

0.636 

0.694 

"•57 

4291.630 

0.134 

1-439 

•553 

13-31 

0.098 

1.059 

1.148 

12-53 

0.058 

0.636 

0.694 

"•57 

RESULTS    FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1908. 


93 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  166.     1908,  Aug.  27,  6h  45m  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.6  mm.     Quality,  good. 


p-P 


sec  i? 


—  O.2 

G 

IS4-  1 

24.2 

25.2 

64.8 

17.0 

1.046 

o-n 

79.6 

40.1 

40.6 

49-4 

II.O 

1.019 

p 

—  20.  i 

55-6 

SS-9 

34-1 

8.6 

I.  Oil 

D 

7-i 

70.8 

70.9 

19.1 

7-5 

1.009 

Diameter 

168.8  mm 

78.3 

78.4 

n.6 

7-3 

1.008 

Factor 

1.019 

85.8 

85.8 

4.2 

7-i 

1.008 

*- 

4!* 

*- 

«M 

0  = 

* 

A 

11 

,-M, 

* 

A 

V 

.  +  ,, 

a 

A 

V 

.  +  ,, 

• 

b 

4196.699 

0.172 

km 
1.892 

km 
2.028 

14.44 

0.168 

km 

1.847 

km 

1.981 

14.36 

0.158 

km 
-738 

ktt 

1.867 

14-03 

4197-257 

0.174 

1.912 

2.048 

14-58 

0.168 

1.847 

1.981 

14-36 

0.158 

-738 

.867 

14.03 

4203.730 

0-173 

1.898 

2-034 

14.48 

0.169 

1-853 

1.987 

14.40 

0.159 

•745 

.874 

14.08 

4207.566 

0.176 

1.930 

2.066 

14.71 

0.169 

1.852 

1.986 

14-39 

o.i  60 

•751 

.880 

14.12 

4216.136 

0.176 

I-925 

2.061 

14.67 

o.i  68 

I-837 

I.97I 

14.29 

o.i  60 

•749 

.878 

14.10 

4220.509 

0.178 

1-944 

2.080 

14.81 

0.171 

i.  86  1 

1-995 

14.46 

o.i  60 

.748 

.877 

14.09 

4232.887 

0.178 

1.936 

2.072 

14-75 

0.169 

1.839 

1-973 

14.30 

0.161 

•752 

.881 

14-13 

4233-328 

0.178 

1.936 

2.072 

14-75 

0.172 

1.869 

2.003 

14-52 

0.162 

.761 

.890 

14.20 

4257-815 

0.179 

1-933 

2.069 

14-73 

0.171 

1.849 

1-983 

14-37 

0.162 

•750 

.879 

14.11 

4258.477 

0.177 

I-9I3 

2.049 

14-59 

0-173 

1.868 

2.  OO2 

14-51 

0.162 

•750 

.879 

14.11 

4265.418 

0.177 

1-907 

2.043 

14-55 

0-173 

1.863 

1-997 

14.47 

0.161 

•737 

.866 

14.02 

4266.081 

0.178 

1.916 

2.052 

14.62 

0.172 

1.846 

1.980 

14-35 

0.162 

1-747 

.876 

14.09 

4268.915 

0.178 

1.916 

2.052 

14.62 

0.172 

1-845 

1-979 

14-34 

0.162 

1-745 

.874 

14-07 

4276.836 

0.178 

I-9I3 

2.049 

14-59 

0.173 

1.854 

1.988 

14.41 

0.161 

1-729 

.858 

13.96 

4283.169 

0.177 

1.898 

2.034 

14.48 

0.172 

1.844 

1.978 

14-33 

0.162 

1-738 

.867 

14-03 

4284.838 

0.176 

1.886 

2.O22 

H-39 

0.171 

1-833 

1.967 

14.26 

0.162 

1-737 

.866 

14.02 

4287.566 

0.177 

1.898 

2.034 

14.48 

0.173 

1-853 

1.987 

14.40 

0.162 

•737 

.866 

14.02 

4288.310 

0.179 

1.916 

2.052 

14.61 

0.172 

1.842 

1.976 

14.32 

0.163 

•747 

.876 

14.09 

4289.525 

0.178 

1.906 

2.042 

14-54 

0.174 

1-863 

1-997 

14-47 

0.163 

•747 

.876 

14.09 

4290.377 

0.178 

1-905 

2.041 

14-53 

0-173 

1.851 

1.985 

14-39 

0.162 

•737 

.866 

14.02 

4290.542 

0.179 

1-915 

2.O5I 

14.60 

0.172 

1.841 

1-975 

14.28 

0.163 

•747 

1.876 

14.09 

4291.630 

0.176 

1-885 

2.021 

14-38 

0.173 

1.851 

1.985 

14-39 

0.164 

.756 

1.885 

H-iS 

0  = 

34U 

0  = 

4*4 

0  = 

64:8 

- 

4196.699 

0.130 

1-434 

1.548 

13.27 

0.096 

1.065 

•154 

12-59 

0-055 

0.622 

0.680 

"•34 

4197.257 

0.129 

.424 

1-538 

13-19 

0.094 

1.045 

•134 

12.37 

0.054 

0.612 

0.670 

11.17 

4203.730 

0.132 

•451 

1-565 

13-42 

0.096 

1.064 

•153 

12.58 

0.056 

0.628 

0.686 

11.42 

4207.566 

0.131 

.441 

1-555 

13-33 

0.098 

1.086 

•175 

12.82 

0.057 

0.637 

0.695 

11.58 

4216.136 

0.130 

.426 

1.540 

13.20 

0.096 

1.  060 

.149 

12.54 

0.057 

0.636 

0.694 

11-57 

4220.509 

0.134 

.468 

1.582 

13-57 

0.096 

1.059 

.148 

12.52 

0.058 

0.646 

0.704 

"•74 

4232.887 

0-133 

•451 

1-565 

13-42 

0.097 

1.065 

•154 

12.59 

0.057 

0.635 

0.693 

11.56 

4233.328 

0-134 

.462 

I-576 

13-51 

0.096 

1-055 

•144 

12.48 

0.056 

0.625 

0.683 

11.38 

4257-815 

0-134 

•453 

1-567 

13-44 

0.098 

1.069 

.158 

12.63 

0.058 

0.638 

0.696 

11-59 

4258.477 

0.136 

•474 

1.588 

13.62 

0.098 

1.069 

.158 

12.63 

0.058 

0.638 

0.696 

"•59 

4265.418 

0-135 

•458 

1-572 

13-47 

0.097 

1-053 

.142 

12.46 

0.057 

0.627 

0.685 

11.40 

4266.081 

0-134 

.448 

1.562 

I3-38 

0.097 

1-053 

.142 

12.46 

0.058 

0.637 

0.695 

11.58 

4268.915 

0-135 

-458 

1-572 

13-47 

0.098 

1.063 

•152 

12.57 

0.058 

0.637 

0.695 

11.58 

4276.836 

0.134 

•443 

1-557 

13-34 

0.098 

1.062 

•IS' 

12.56 

0.057 

0.627 

0.685 

11.40 

4283.169 

0.134 

.441 

1-555 

13-33 

0.098 

1.062 

•151 

12.56 

0.058 

0.637 

0.695 

11.58 

4284.838 

0-135 

•451 

1-565 

13-42 

0.098 

1.061 

-ISO 

12-55 

0.059 

0.646 

0.704 

11.74 

4287.566 

0-134 

.440 

1-554 

13-32 

0.098 

1.061 

.150 

12-55 

0.057 

0.626 

0.684 

"•39 

4288.310 

0.134 

•440 

1-554 

13-32 

0.097 

1.051 

.140 

12-44 

0.058 

0.636 

0.694 

"•57 

4289.525 

0-135 

1.450 

1-564 

13-41 

0.098 

1.061 

•ISO 

12-55 

0.059 

0.646 

0.704 

n-74 

4290.377 

0.134 

1-439 

1-553 

I3-3I 

0.098 

i.  060 

.149 

12.54 

0.057 

0.626 

0.684 

"•39 

4290.542 

0.134 

1-439 

1-553 

I3-3I 

0.098 

i.  060 

•149 

12.54 

0.058 

0.636 

0.694 

11-57 

4291.630 

0-135 

1-449 

1-563 

13-40 

0.009 

1.070 

•159 

12.65 

0.058 

0.636 

0.694 

11-57 

94      AN  INVESTIGATION  OF  THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 


TABLE  n.  —  RESULTS  TOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908 — -Continued. 

Plates  o>  179  and  a  180.     1908,  Sept.  30,  nh  40™  G.  M.  T.     ^Measured  by  L.  on  T.     Distance  from  Limb  i.o  mm.     Quality,  good. 

p— P          -w  <t>  T}  secy 

29.2         29.9        60.1         13.5         1.028 


O       187.4 

o-n   112.9 
p     -26.2 


D  6.7 

Diameter  170.6  mm 

Factor        1.012 


X 

<t>  =  6oti 

•t>  =  6o!i 

<t>  =  60!  I 

<t>  =  6o°i 

A 

»3 

v  +  v1 

* 

A 

» 

»  +  », 

1 

A 

I) 

»  +  », 

J 

A 

V 

P  +  Bj 

£ 

km 

km 

0 

km 

km 

0 

km 

km 

0 

km 

km 

0 

4196.699 

0.070 

0-779 

0.852 

12.14 

0.070 

0-779 

0.852 

12.14 

0.064 

0.718 

0.791 

11.27 

0.065 

0.728 

0.801 

11.41 

4197-257 

0.070 

0.779 

0.852 

12.14 

0.070 

0.779 

0.852 

12.14 

0.065 

0.728 

0.801 

11.41 

0.065 

0.728 

0.801 

11.41 

4203.730 

0.070 

0.778 

0.851 

12.12 

0.070'    0.779 

0.852 

12.14 

0.065 

0.726 

0.799      "-38 

0.065 

0.727 

0.800 

11.40 

4207.566 

0.072 

0.797 

0.870 

12.39 

0.071 

0.787 

0.860 

12.25 

0.065 

0.725 

0.798 

u-37 

0.066 

0-735 

0.808 

11.51 

4216.136 

0.071 

0.786 

0.859 

12.24 

0.070 

0.776     0.849 

12.09 

0.064 

0.714 

0.787 

II.  21 

0.065 

0.723 

0.796 

n-34 

4220.509 

0.072 

Q-795 

0.868 

12.36 

0.072 

0.795    0.868 

12.37 

0.066 

0.732 

0.805 

11.47 

0.067 

0.741 

0.814 

"•59 

4232.887 

0.072 

0-793 

0.866 

12-33 

0.072 

0.794 

0.867 

12-35 

0.065 

0.720 

0-793 

11.29 

0.065 

0.720 

0-793 

11.29 

4233-328 

0.072 

0-793 

0.866 

12-33 

0.073 

0.803 

0.876 

12.48 

0.066 

0.730 

0.803 

11.44 

0.066 

0.730 

0.803 

11.44 

4257-815 

0.074 

0.808 

0.881 

12-55 

0.074 

0.808 

0.881 

12-55 

0.068 

0.746 

0.819 

11.67 

0.067 

0-735 

0.808 

11.51 

4258.477 

0.072 

0.788 

0.861 

12.26 

0.072 

0.788    0.86  1 

12.26 

0.067 

0.736 

0.809 

11.52 

0.067 

0-735 

0.808 

11.51 

4265.418 

0.072 

0.787 

0.860 

12.25 

0.073 

0.798 

0.871 

12.40 

0.068 

0.744 

0.817 

11.64 

0.067 

0.734 

0.807 

11.49 

4266.081 

0.073 

0-797 

0.870 

12.39 

0.074 

0.808 

0.881 

12.55 

0.068 

0.744 

0.817 

11.64 

0.069 

0-754 

0.827 

11.78 

4268.915 

0.072 

0.787 

0.860 

12.25 

0.074 

0.807 

0.880 

12.53 

0.068 

0-744 

0.817 

11.64 

0.067 

0-734 

0.807 

11.49 

4276.836 

0.074 

0.805 

0.878 

12.51 

0.074 

0.806 

0.879 

12.52 

0.067 

0-733 

0.806 

11.48 

0.068 

0-743 

0.816 

11.62 

4283.169 

0.072 

0.783 

0.856 

12.19 

0.073 

0.794 

0.867 

12-35 

0.067 

0.732 

0.805 

11.47 

0.067 

0-733 

0.806 

11.48 

4284.838 

0.072 

0.783 

0.856 

12.19 

0.074 

0.804 

0.877 

12.49 

0.068 

0.742 

0.815 

11.61 

0.067 

0-733 

0.806 

11.48 

4287.566 

0.073 

0.792 

0.865 

12.35 

0.074 

0.803 

0.876 

12.48 

0.068 

0.742 

0.815 

ii.  61 

0.068 

0-742 

0.815 

II.OI 

4288.310 

0.074 

0.802 

0.875 

12.47 

0.073 

0-793 

0.866 

12.34 

0.068 

0.742 

0.815 

11.61 

0.067 

0.732 

0.805 

11.47 

4289.525 

0.074 

0.802 

0.875     12.47 

0.074 

0.803 

0.876 

12.48 

0.069 

0.752 

0.825 

"•75 

0.068 

0.742 

0.815 

ii.  61 

4290.377 

0.073 

0.792 

0.865 

12.32 

0.072 

0.783 

0.856 

12.20 

0.068 

0.742 

0.815 

11.61 

0.067 

0.732 

0.805 

11.47 

4290.542      0.073!  0.792 

0.865 

12.32 

0.073 

0-793 

0.866 

12-34 

0.067 

0.730 

0.803 

11.44 

0.069 

0.752 

0.8251    11.75 

4291.630 

0.074 

0.802 

0.875 

12.47 

0.073 

0-793 

0.866 

12.34 

0.068 

0.740 

0-813 

n-59 

0.071 

0.772 

0.845 

12.04 

Plate  w  182.     1908,  Oct.  9,  nh  om  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  i.o  mm.     Quality,  good. 

p  —  P          TT  <f  V  secy 


G 

o-n 
p 


196.2 

121.7 

—26.5 


—  O.I 

55-9 
70.9 
78.9 


56.1 
71.0 
79-o 


33-9 
19.0 
i  i.o 


7-4 
6-5 
6-3 


1.008 
i. 006 
i. 006 


D  6.1 

Diameter  172.6  mm 

Factor       i  .01 2 


\ 

<t>  = 

II°O 

0  = 

n?o 

0  = 

iQ?o 

0  = 

33?9 

A 

A 

V 

fl  +  Hj 

£ 

A 

1! 

»  +  *, 

J 

A 

11 

»  +  », 

{ 

A 

•a 

»  +  »i 

« 

km 

km 

0 

km 

km 

0 

km 

km 

0 

km 

km 

» 

4196.699 

0.169 

1.843 

1.981 

14-33 

0.169 

1.843 

1.981 

14-33 

0-157 

.711 

1-845 

13.85 

0.125 

1-365 

1.485 

12.70 

4197-257 

0.170 

1.852 

1.990 

14-39 

0.170 

1.852 

1.590 

14-39 

0.158 

.721 

1.855 

13.93 

0.125 

.365 

I.48S 

12.70 

4203.730 

0.171 

1.861 

1.999 

14.46 

0.172 

1.872 

2.009 

14-53 

0.157 

•70S 

1.839 

13.81 

0.127 

•384 

1.504 

12.86 

4207.566 

0.172 

1.869 

2.007 

14-52 

0.172 

1.865 

2.OO2 

14.48 

o.i  60 

•731 

1.865 

14.00 

0.127 

•382 

1.502 

12.85 

4216.136 

0.172 

1.  860 

1.998 

14-45 

0.171 

1.852 

1.990 

14-39 

0.159 

.718 

1.852 

13.91 

0.126 

.367 

1.487 

12.72 

4220.509 

0.172 

1.858 

1.996 

14.44 

0.172 

1.856 

1.994 

14.42 

0.160 

.725 

1.  860 

13-97 

0.126 

•366 

1.486 

12.71 

4232.887 

0.173 

1-865 

2.003 

14.49 

0.173 

1.863 

2.OOI 

:4-47 

o.i  60 

.724 

1.859 

13.96 

0.128 

.381 

I.50I 

12.84 

4233-328 

0.173 

1.865 

2.003 

14.49 

0.172 

1.853 

I.99I 

14.40 

0.161 

•734 

1.868 

14.03 

0.126 

•360 

1.480 

12.66 

4257-815 

0.175 

1.874 

2.OI2 

14-55 

0.172 

1.843 

1.981 

14-33 

o.i  60 

.712 

1.846 

13.86 

0.128 

•372 

1.492 

12.77 

4258-477 

0.174 

1.863 

2.OOI 

14-47 

0.174 

1.862 

2.000 

14.46 

0.160 

.712 

1.846 

13.86 

0.127 

•362 

1.482 

12.68 

4265.418 

0.174 

1.859 

1-997 

14.44 

0-173 

1.848 

1.986 

14-36 

0-159 

1.697 

1.831 

13-75 

0.127 

.361 

1.481 

12.67 

4266.081 

0.174 

1.859 

1.997 

14.44 

0.174 

1.859 

1.997 

14.44 

0.161 

1-715 

1.849 

13-88 

0.129 

.380 

1.500 

12.83 

4268.915 

0.174 

1-855 

1-993 

14.41 

0.174 

1.856 

1.994 

14.42 

0.161 

1.714 

1.848 

13.88 

0.126 

•347 

1.467 

12-55 

4276.836 

0.173 

1.843 

1.981 

14-33 

0.173 

I-843 

1.981 

14-33 

o.iS9 

1.693 

1.827 

13.72 

0.126 

•345 

I-465 

12.53 

4283.169 

0.173 

1-838 

1.976 

14.29 

0.174 

1.848 

1.986 

14.36 

0-159 

1.689 

1.823 

13.69 

0.127 

•352 

1.472 

12-59 

4284.838 

0.174 

1.848 

1.986 

14.36 

0.173 

1.837 

1-975 

14.28 

0.160 

1.699 

1-833 

13.76 

0.127 

•352 

1.472 

12.59 

4287.566 

0.174 

1.847 

1.985 

14-35 

O.I7S 

I-857 

'•995 

14.42 

0.160 

1.698 

1.832 

13.76 

0.127 

•351 

1.471 

12.58 

4288.310 

0.174 

1.847 

1.985 

14.35 

0.174 

1.847 

1.985 

14-35 

o.i  60 

1.698 

1.832 

13.76 

0.127 

•351 

1.471 

12.58 

4289.525 

0.173 

1.836 

1-974 

14.28 

0.175 

1.856 

1.994 

14.41 

o.i  60 

1.698 

1-832 

13.76 

0.128 

.361 

1.481 

12.67 

4290.377 

0.173 

1.836 

1-974 

14.28 

0-175 

1.856 

1.994 

14.41 

0.159 

1.688 

1.822 

13.68 

0.128 

.361 

1.481 

12.67 

4290.542 

0.174 

1.846 

1.984 

14-35 

0-175 

1.856 

1.994 

14.41 

0.159 

1.688 

1.822 

13.68 

0.128 

.361 

1.481 

12.67 

4291.630 

0.172 

1-825 

1.963 

14.20 

0-175 

1.856 

1.994 

14.41 

0-157 

1.718 

1.852 

13.91 

0.128 

.361 

1.481 

12.67 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1908. 


95 


TABLE  it. — RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  183.     1908,  Oct.  9,  nh  om  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  i.o  mm.    Quality,  good. 


P-F 


secv 


—  O.I 

G       196.2 

55-9 

56.1 

33-9 

7-4 

i.  008 

o-n   121.7 

70.9 

71.0 

19.0 

6-5 

i.  006 

P     -26.5 

78.9 

79.0 

II.O 

6-3 

i.  006 

D            6.1 

Diameter  172.6  mm 

Factor        1.012 

0  = 

i.?o 

0  = 

.* 

0  = 

19*0 

0  = 

.0!0 

A 

V 

.  +  ,, 

8 

A 

D 

„  +  ,, 

£ 

A 

ii 

»  +  r, 

1 

A 

V 

*  +  ., 

£ 

4196.699 

0.170 

km 
1-851 

km 
1.989 

o 

14.38 

0.170 

km 

.851 

km 

1.989 

14-38 

0.158 

km 

.722 

km 

1.856 

13-94 

0.158 

km 

1.722 

km 
.856 

13-94 

4197-257 

0.169 

1.841 

1-979 

14-31 

0.170 

.851 

1.989 

14.38 

0.158 

.722 

1.856 

13-94 

0.158 

1.722 

-856 

13-94 

4203.730 

0.172 

1.870 

2.008 

14-52 

0.173 

.878 

2.016 

14.58 

o.i  60 

•741 

I-875 

14.08 

0.159 

1.729 

.863 

13-99 

4207.566 

0.171 

1.854 

1-992 

14.41 

0.171 

•8S4 

1-992 

14.41 

0.161 

•749 

1.883 

14.14 

o.i  60 

1.738 

.872 

14.06 

4216.136 

0.171 

1.851 

1.989 

14-38 

0.171 

.851 

1.989 

14-38 

0.159 

.726 

1.860 

13-97 

o.i  60 

1-734 

.868 

14.03 

4220.509 

0.172 

I.8S5 

1-993 

14.41 

0.174 

.878 

2.016 

14.58 

o.i  60 

•734 

1.868 

14-03 

o.i  60 

1-732 

.866 

14.01 

4232.887 

0.171 

1.842 

1.980 

14-32 

0.174 

.875 

2-013 

H-S6 

0.162 

•745 

1.879 

14.11 

o.i  60 

1-725 

•859 

13.96 

4233-328 

0.172 

1.852 

1.990 

14-39 

0.173 

.864 

2.OO2 

14.48 

0.161 

•735 

1.869 

14-03 

0.161 

1-735 

.869 

14-03 

4257-8IS 

0.174 

1.862 

2.000 

14-46 

0.174 

.861 

1-999 

14.46 

0.164 

•755 

1.889 

14.18 

0.162 

1-734 

.868 

14.02 

4258.477 

0.174 

I.86I 

1-999 

14.46 

0.174 

.861 

1-999 

14.46 

0.161 

•724 

1.858 

13-95 

0.161 

1-724 

-858 

13-95 

4265.418 

0.174 

I.857 

1-995 

14-43 

0.174 

.857 

1-995 

14-43 

0.161 

.721 

1-855 

13-93 

0.161 

1.724 

.858 

13-95 

4266.081 

0.175 

1.867 

2.005 

14-50 

0-173 

.846 

1.984 

14-45 

0.162 

-730 

1.864 

14.00 

0.162 

1-734 

.868 

14.02 

4268.915 

0.174 

1.855 

1-993 

14.41 

0.174 

.855 

1-993 

14.41 

0.162 

•729 

1.863 

13-99 

0.162 

1.729 

-863 

13-99 

4276.836 

0.174 

1.862 

2.OOO 

14.46 

0-175 

.863 

2.001 

14-47 

0.162 

.726 

i.  860 

13-97 

0.161 

1.716 

.850 

13.90 

4283.169 

0.174 

1.848 

1.986 

14-37 

0.176 

.867 

2.OO5 

14.50 

0-163 

•731 

1.865 

14.00 

0.162 

1.721 

.855 

13-93 

4284.838 

0.174 

1.847 

1.985 

14-36 

0.175 

•857 

•995 

14-43 

0.162 

.721 

1-855 

13-93 

0.162 

.721 

•855 

13-93 

4287.566 

0.174 

1.846 

1.984 

14-35 

0.175 

-856 

•994 

14.42 

0.163 

•731 

1.865 

14.00 

0.161 

.710 

.844 

13-85 

4288.310 

0.174 

1.846 

1.984 

14-35 

0.174 

.846 

•984 

14-35 

0.162 

.720 

1-854 

13.92 

0.162 

.720 

•854 

13-92 

4289.525 

0.175 

I.855 

1-993 

14.41 

0.175 

-855 

-993 

14.41 

0.162 

•719 

1-853 

13-91 

0.162 

-719 

.853 

13.92 

4290.377 

0.173 

I.835 

1-973 

14-27 

0-175 

-855 

•993 

14.41 

0.162 

.719 

1-853 

13-91 

0.161 

.709 

1.843 

13-84 

4290.542 

0.175 

1.855 

1-993 

14.41 

0.176 

.865 

2.003 

14.48 

0.164 

•739 

1-873 

14.06 

0.162 

.719 

1-853 

13-91 

4291.630 

0.175 

1.855 

1-993 

14.41 

0-7I5 

•855 

1-993 

14.41 

0.162 

•719 

1-853 

13-91 

0.162 

.719 

I.8S3 

13-91 

0  = 

ig°o 

0  = 

33!, 

0  = 

33^9 

0  = 

33  °9 

4196.699 

0.159 

1.732 

1.866 

14.01 

0.131 

•431 

•551 

13-27 

0.130 

1.420 

1.540 

13-17 

0.129 

1.411 

•531 

13.10 

4197-257 

0.159 

1-732 

1.866 

14.01 

0.131 

•431 

•551 

13.27 

0.130 

1.420 

1-540 

13-17 

0.130 

1.420 

•540 

13-17 

4203.730 

o.i  60 

1-741 

1-875 

14.08 

0.132 

•439 

•559 

13-33 

0.132 

1.438 

I.558 

13-33 

0.131 

1.428 

.548 

13-24 

4207.566 

o.i  60 

1.738 

1.872 

14.06 

0.132 

•437 

•557 

13-32 

0.132 

1-437 

1-557 

13-32 

0.131 

1-425 

•545 

13.22 

4216.136 

o.i  60 

1-735 

1.869 

14.03 

0.131 

.419 

•539 

13.16 

0.130 

.416 

I-536 

13-14 

0.131 

1-423 

•543 

13.20 

4220.509 

0.160 

1.732 

1.866 

14.01 

0.131 

.418 

-538 

13.16 

0.132 

•432 

1-552 

13-28 

0.132 

1-432 

-552 

13.28 

4232-887 

0.161 

1-736 

1.870 

14.04 

0.132 

.426 

•546 

13.22 

o.i34 

.446 

1.566 

13-39 

0.132 

1-429 

•549 

13-25 

4233-328 

o.i  60 

1-724 

1.858 

13-95 

0.132 

.426 

•546 

13.22 

0.133 

•436 

1.556 

13-31 

0.134 

1-447 

.567 

13-40 

4257-8I5 

0.161 

1.724 

1-858 

13-95 

0.135 

•449 

•569 

13-42 

0-I3S 

•449 

1.569 

13-41 

0.134 

1-437 

•557 

13-32 

4258.47? 

0.162 

1-734 

1.868 

14.03 

0.134 

•438 

-558 

13-33 

0-134 

•438 

I.558 

13-33 

0.132 

1.417 

•537 

13-15 

4265.418 

0.161 

1.721 

1-855 

13-93 

0.132 

•413 

•533 

13-11 

0.133 

.424 

1-544 

13.21 

0.133 

1.424 

•544 

13.21 

4266.081 

0.162 

i-73i 

1.865 

14.00 

0.133 

•423 

•543 

13.20 

0.134 

•434 

1-554 

13.29 

0.133 

1-424 

•544 

13-21 

4268.915 

0.162 

1.727 

1.861 

13-97 

0.134 

•432 

•552 

13.28 

0.135 

•444 

1-564 

13-38 

0-134 

1-432 

•552 

13.27 

4276.836 

0.116 

1.849 

13-89 

0.134 

•431 

•551 

13-27 

0.134 

•431 

i-SSi 

13-27 

0.133 

1.420 

•540 

13-17 

4283.169 

0.126 

1.721 

I-85S 

13-93 

0.134 

•427 

•547 

13-23 

0.134 

.426 

I-546 

13.22 

o.i33 

1.417 

•537 

13-15 

4284.838 

0.161 

1.711 

1.845 

13-85 

0.134 

.427 

•547 

13-23 

0.134 

.426 

1.546 

13.22 

0.132 

1.407 

.527 

13-06 

4287.566 

0.161 

1.711 

1-845 

13-85 

0-134 

.426 

•546 

13.22 

0.133 

•415 

1-535 

13-13 

0.134 

1-429 

•549 

13-25 

4288.310 

0.162 

1.720 

1.854 

13-92 

0.134 

•425 

•545 

13.22 

0.133 

•415 

1-535 

I3-I3 

0-133 

1.419 

•539 

13.16 

4289.525 

0.162 

1-719 

1-853 

13-91 

0-135 

•435 

•555 

13-30 

0-133 

•415 

1-535 

13-13 

0.134 

1.429 

•549 

13-25 

4290.377 

0.161 

1.709 

1-843 

13-84 

0.135 

•435 

•555 

13-30 

0-135 

•435 

1-555 

I3-30 

0-133 

1-419 

•539 

13.16 

4290.542 

0.162 

1-7I9 

1-853 

13-91 

0.134 

•425 

•545 

13.22 

0.135 

•435 

1-555 

13-30 

0-134 

1.429 

1-549 

13-25 

4291.630 

0.163 

1.729 

1-863 

13-99 

0.135 

I-43S 

•555 

13-30 

0.134 

•425 

1-545 

13.22 

0.136 

1.446 

1.566 

13-39 

96      AN  INVESTIGATION  OF  THE   ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC   METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1908 — -Continued. 
Plate  w  184.     1908,  Oct.  22,  6h  30'"  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.3  mm.     Quality,  good. 


P-f 


sec*? 


o.o 

0 

209.0 

24.0 

24-5 

6S.5 

12.5 

1.024 

O-Q 

I34-S 

29-3 

29.7 

60.3 

10.5 

1.017 

P 

-25-9 

39-7 

40.0 

50.0 

8.1 

I.OIO 

D 

5-i 

86.0 

86.0 

4.0 

5-2 

1.004 

Diameter 

171.2  mm 

Factor 

1.015 

\ 

*-* 

0  =  5o°o 

0  =  So!o 

A 

A 

V 

.  +  „ 

f 

A 

' 

.  +  ,, 

s 

A 

• 

,  +  „ 

« 

4196.699 

0.176 

km 
1.920 

km 
2.060 

14.66 

0.092 

km 

I.OIO 

km 
.109 

o 

12.25 

0.093 

km 
I.O2O 

km 
I.II9 

0 

12.36 

4197-257 

0.176 

1.920 

2.060 

14.66 

0.092 

I.OIO 

.109 

12.25 

0.093 

I.O2O 

1.119 

12.36 

4203.730 

0.176 

I-9I5 

2-055 

14.62 

0.093 

1.017 

.116 

12-33 

0.094 

1.030 

1.129 

12.47 

4207.566 

0.177 

1.924 

2.064 

14.69 

0.093 

1.015 

.114 

12.30 

0.094 

1.028 

1.127 

12.45 

4216.136 

0-177 

1.919 

2.059 

14-65 

0.092 

1.004 

•103 

12.18 

0.094 

1.023 

1.  122 

12.39 

4220.509 

0.178 

1.928 

2.068 

14-72 

0.094 

1.023 

.122 

12.39 

0.095 

1.032 

1.131 

12.49 

4232-887 

0.178 

.921 

2.061 

14.67 

0.094 

1.  020 

.119 

12.36 

0.094 

1.020 

I.II9 

12.36 

4233-328 

0.180 

.941 

2.081 

14.81 

0.095 

1.030 

.129 

12.47 

0.095 

1.030 

I.I29 

12.47 

4257-815 

0.180 

.928 

2.068 

14.72 

0.094 

1.013 

.112 

12.28 

0.097 

1.043 

1.142 

I2.6l 

4258-477 

0.179 

.918 

2.058 

14-65 

0.095 

1.023 

.122 

12.39 

0.095 

I.O22 

1.  121 

12.38 

4265.418 

0.179 

.914 

2-054 

14.62 

0.094 

I.OI2 

.III 

12.27 

0.094 

I  .Oil 

i.  no 

12.26 

4266.081 

0.181 

•934 

2.074 

14.76 

0.096 

1.032 

•131 

12.49 

0.095 

1.  02  I 

1.  1  20 

12.37 

4268.915 

0.180 

.921 

2.061 

14.67 

0.094 

I.OO9 

.108 

12.24 

0.096 

1.030 

1.129 

12-47 

4276.836 

0.180 

.919 

2.059 

14-65 

0.094 

1.008 

.107 

12.23 

0.096 

I.O29 

1.128 

12.46 

4283.169 

0.180 

•913 

2-053 

14.61 

0.095 

1.016 

•"5 

12.32 

0.097 

1.036 

I-I35 

12-54 

4284.838 

0.180 

•913 

2-053 

14.61 

0.095 

1.016 

.115 

12.32 

0.097 

1.036 

'•'35 

12-54 

4287.566 

0.180 

.912 

2.052 

14.60 

0.094 

1.005 

.104 

12.19 

0.096 

I.O26 

1.125 

12-43 

4288.310 

0.179 

.902 

2.042 

14-53 

0.095 

1.015 

.114 

12.30 

0.097 

1.036 

I-I35 

12.54 

4289.525 

0.180 

.912 

2.052 

14.60 

0.097 

1.036 

•135 

12.54 

0.098 

1.046 

I-I45 

12.65 

4290.377 

0.180 

.912 

2.052 

14.60 

0.094 

1.005 

1.104 

12.19 

0.096 

1-025 

1.124 

12.41 

4290.542 

0.180 

.912 

2.052 

14.60 

0.095 

1.015 

1.114 

12.30 

0.098 

1.046 

I-I45 

12.65 

4291.630 

0.181 

.922 

2.062 

14.67 

0.095 

1.015 

1.114 

12.30 

0.097 

1.035 

I-I34 

12.52 

\ 

,  =  60:3 

<t>  =  6o°3 

*  =  65:s 

*  =  65!S 

A 

A 

V 

,  +  ., 

« 

A 

D 

M-i 

1 

A 

V 

.  +  ,, 

£ 

A 

V 

.  +  ., 

s 

4196.699 

0.065 

km 
0.719 

km 
0.799 

"•45 

0.066 

km 
0.729 

km 

0.805 

iJ-59 

0-053 

km 

0.589 

km 

0.657 

11.25 

0-053 

km 

0.588 

km 
0.656 

11.23 

4I97-257 

0.066 

0.729 

0.805 

"•59 

0.066 

0.729 

0.805 

"•59 

0.054 

0.600 

0.668 

11.44 

0-053 

0.588 

0.656 

11.23 

4203.730 

0.068 

0.750 

0.830 

11.89 

0.067 

0-739 

0.815 

11.74 

0.053 

0.588 

0.656 

n-57 

0.054 

0.598 

0.666 

11.40 

4207.566 

0.068 

0.749 

0.825 

11.88 

0.067 

0-739 

0.815 

11.74 

0.054 

0.598 

0.666 

11.40 

0.054 

0-597 

0.665 

11.38 

42l6.I36 

0.067 

0.738 

O.SlS 

11.72 

0.066 

0.728 

0.808 

11.58 

0.053 

0.586 

0.654 

n.  20 

0.053 

0.585 

0-653 

11.18 

422O.5O9              O.O68 

0.746 

0.826 

11.84 

0.068 

0.746 

0.82^ 

11.84 

0-053 

0.584 

0-652 

ii.  16 

0-053 

0.584 

0.652 

ii.  16 

4232.887 

0.069 

0-754 

0.834 

"•95 

0.067 

0-734 

11.66 

0-055 

0.605 

0.673 

11.52 

0-053 

0.583 

0.651 

11.14 

4233-328 

0.068 

0-744 

0.824 

11.81 

0.070 

0.764 

0.84/ 

12.09 

0.054     0.593 

0.66  1 

11.32 

0.054 

0-593 

0.661 

11.32 

4257-8I5 

0.068 

0-739 

o.Sic 

11.74 

0.070 

0.758 

0.838 

12.01 

0.055     0.600 

0.668 

11.44 

0.055 

0.601 

0.669 

"•45 

4258.477    !  0.068 

0-739 

0.819 

11.74 

0.069 

0.748 

0.828 

11.86 

0-055 

0.600 

0.668 

n-44 

0.055 

0.601 

0.669 

11-45 

4265.418 

0.069 

0.748 

0.828 

11.86 

0.070 

0.758 

0.838 

12.01 

0.053 

0.578 

0.646 

1  1.  06 

0.055 

0.600 

0.668 

11.44 

4266.081 

0.069 

0.748 

0.828 

11.86 

0.069 

0.748 

0.828 

11.86 

0.057 

0.622 

0.690 

11.81 

0.056 

0.610 

0.678 

n.  61 

4268.915 

0.069 

0.746    0.826 

11.84 

0.070 

0-757 

0-837 

11.99 

0.056 

0.610 

0.678 

1  1.  6  1 

0.056 

0.609 

0.677 

"•59 

4276.836 

0.068 

0-734 

O.8l<! 

11.86 

0.071 

0.766 

0.84^ 

12.12 

0.056 

0.609 

0.677!    11.59 

0.054 

0.587 

0-655 

II.  21 

4283.169 

0.069 

0-743 

0.823 

11.79 

0.068 

0-733 

0.813 

11.65 

0.056 

0.607 

0.675!    11.56 

0.054 

0.586 

0.654 

II.  20 

4284.838 

0.070 

0-754 

0.834 

"•95 

0.069 

0.743 

0.823 

11-79 

0.055 

0-597 

0.665 

ii.  61 

0.054 

0.586 

0.654 

II-54 

4287.566 

0.068 

0-734 

O.8l<: 

11.66 

0.069 

0-743 

0.823 

11.79 

0-055 

0.596 

o.66<: 

n-37 

0.055 

0.596 

0.664 

ii-54 

4288.310 

0.067 

0.723 

0.803 

11.51 

0.070 

0-753 

0.833 

11-94 

0.056 

0.606 

0.674 

n-54 

0-055 

0.596 

0.664 

11-37 

4289.525 

0.070 

o-753|    0.833 

11.94 

0.070 

0-753 

0-833 

11.94 

0.056 

0.606 

0.674 

"•54 

0.057 

0.617 

0.685 

"•73 

4290.377 

0.070 

0-753 

0.833 

11.94 

0.069 

0-742 

0.822 

11.78 

0.056 

0.606 

0.674 

n-54 

0.054 

0.585 

0.653 

ii.  18 

4290.542 

0.070 

0-753 

0.833 

11.94 

0.071 

0.763 

0.843 

1  2.08 

0.057 

0.616 

0.684 

11.71 

0.056 

0.606 

0.674 

"•54 

4291.630 

0.069 

0-743 

0.823 

11.79 

0.070 

0-753 

0-833 

11-94 

0.056 

0.606 

0.674 

n-54 

0-055 

0-595 

0.663 

"•35 

RESULTS   FOR   INDIVIDUAL   PLATES.      OBSERVATIONS   OF    1908. 


97 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  or  1908  —  Continued. 
Plate  w  185.     1908,  Oct.  22,  6h  3om  G.  M.  T.    Measured  by  L.  on  T.    Distance  from  Limb  1.3  mm.    Quality,  good. 


O       209.0 

0-0     I34-S 

P       -25-9 

D  5.1 

Diameter  171.2  mm 

Factor        1.015 


p-P 

o.o 
24.0 

39-7 
86.0 


24-5 
40.0 
86.0 


65.5 

50.0 

4.0 


12.5 
8.1 
5-2 


sec*) 


1.024 

I.OIO 

1.004 


0  = 

4!° 

0  = 

5o!o 

0  = 

5°!° 

X 

A 

t) 

.  +  ., 

' 

A 

ti 

,-M, 

« 

A 

D 

V  +  Sj 

1 

4196.699 

0.176 

km 
1.920 

km 

2.060 

14.66 

0.091 

km 
0.999 

km 

1.098 

12.13 

0.091 

km 

0.999 

km 
.098 

0 

12.13 

4197.257 

0.176 

1.920 

2.060 

14.66 

0.091 

0.999 

1.098 

12.13 

0.091 

0-999 

.098 

12.13 

4203-730 

0.177 

1.926 

2.066 

14.70 

0.092 

1.008 

.107 

12.23 

0.092 

1.  008 

.107 

12.23 

4207.566 

0.177 

1.924 

2.064 

14.69 

0.092 

1.  006 

.105 

12.21 

0.092 

1.007 

.106 

12.22 

4216.136 

0.177 

1.921 

2.061 

14.67 

0.092 

1.004 

•103 

12.  l8 

0.092 

1.005 

.104 

12.19 

4220.509 

0.178 

1.928 

2.068 

14.72 

0.093 

I.  Oil 

.no 

12.26 

0.092 

1.003 

.102 

12.17 

4232.887 

0.178 

1.921 

2.061 

14.67 

0.092 

0.999 

.098 

12.13 

0.094 

1.015 

.114 

12.30 

4233-328 

O.I  80 

1.941 

2.081 

14.81 

0.093 

1.009 

.108 

12.24 

0.094 

1.015 

.114 

12.30 

4257-815 

0.180 

1.929 

2.069 

14.72 

0.094 

1.013 

.112 

12.28 

0.093 

1-003 

.102 

12.17 

4258.477 

0.180 

1.928 

2.068 

14.72 

0.092 

0.992 

.091 

12.05 

0.093 

1.003 

.102 

12.17 

4265.418 

0.179 

1.914 

2-054 

14.62 

0.094 

I.OIO 

.109 

12.25 

0.094 

I.OIO 

.109 

12.25 

4266.081 

0.181 

1-934 

2.074 

14.76 

0.093 

1.  000 

•099 

12.14 

0.093 

I.OOO 

.099 

12.14 

4268.915 

0.179 

1.911 

2.051 

14.60 

0.094 

1.009 

.108 

12.24 

0.094 

I.OIO 

.109 

12.25 

4276.836 

0.180 

1.919 

2.059 

14.65 

0.093 

0.998 

.097 

12.12 

0.094 

1.008 

.107 

12.23 

4283.169 

0.180 

1.914 

2-054 

14.62 

0.094 

1.  006 

.105 

12.21 

0.094 

1.  006 

.105 

12.21 

4284.838 

0.180 

1.914 

2.054 

14.62 

0.093 

0.996 

•095 

12.  IO 

0.094 

1.  006 

•105 

12.21 

4287.566 

0.180 

I-9I3 

2.053 

14.61 

0.094 

1.005 

.IO4 

12.19 

0.093 

0-995 

1.094 

I  2.  08 

4288.310 

0.181 

1.923 

2.063 

14.68 

0.095 

1.015 

.114 

12.30 

0.093 

0-995 

1.094 

I  2.  08 

4289.525 

0.180 

1.912 

2.052 

14.60 

0.093 

0.995 

.094 

I  2.  08 

0.095 

1.015 

I.II4 

12.30 

4290.377 

0.179 

1.902 

2.042 

14-53 

0.094 

1.005 

.IO4 

12.19 

0.094 

1.005 

I.I04 

12.19 

4290.542 

0.180 

1.912 

2.052 

14.60 

0.094 

1.004 

.103 

12.  18 

0.094 

1.005 

I.I04 

12.19 

4291.630 

0.181 

1.922 

2.062 

14.67 

0.094 

1.004 

.103 

12.18 

0.096 

1.025 

I.I24 

12.41 

0  = 

asts 

0= 

«* 

4196.699 

0.051 

0.567 

0.635 

10.87 

0.050 

0-559 

0.627 

10-73 

4'97-257 

0.051 

0.567 

0.635 

10.87 

0.051 

0.570 

0.638 

10.92 

4203.730 

0.052 

0-577 

0.645 

11.04 

0.052 

0-579 

0.647 

II.OS 

4207.566 

0.051 

0.566 

0.634 

10.85 

0.052 

0-577 

0.645 

II.O4 

4216.136 

0.052 

0.576 

0.644 

11.03 

0.051 

0.564 

0.632 

10.82 

4220.509 

0.052 

0-575 

0.643 

II.OI 

0.052 

0-575 

0.643 

II.OI 

4232.887 

0.054 

0-593 

0.66  1 

11.32 

0.052 

0-573 

0.641 

10.97 

4233-328 

0.054 

0-593 

0.661  ' 

11.32 

0.054 

0-593 

0.661 

11.32 

4257.8i5 

0.054 

0.590 

0.658 

11.26 

0-053 

0.580 

0.648 

11.09 

4258.477 

0.054 

0.590 

0.658 

11.26 

0.052 

0.569 

0.637 

10.90 

4265.418 

0-053 

0-579 

0.647 

11.08 

0.054 

0.589 

0.657 

11.25 

4266.081 

0.055 

0.600 

0.668 

11.44 

0.055 

0.600 

0.668 

11.44 

4268.915 

0-055 

0-599 

0.667 

11.42 

0-055 

o.599 

0.667 

11.42 

4276.836 

0.054 

0.588 

0.656 

11.23 

0.054 

0.587 

0.655 

II.  21 

4283.169 

0.054 

0.587 

0-655 

II.  21 

0.054 

0.586 

0.654 

II.  2O 

4284.838 

0.054 

0.587 

0-655 

II.  21 

0.053 

0.576 

0.644 

11.02 

4287.566 

0.054 

0.586 

0.654 

II.  2O 

0-053 

0-575 

0.643 

II.OI 

4288.310 

0.055 

0.596 

0.664 

11.47 

0.053 

0-575 

0.643 

II.OI 

4289.525 

0.054 

0.586 

0.654 

11.20 

0.053 

0-575 

0.643 

II.OI 

4290.377 

0-053 

0.576 

0.644 

11.02 

0.053 

0-575 

0.643 

II.OI 

4290.542 

0.054 

0.586 

0.654 

1  1.  2O 

0.053 

0-575 

0.643 

II.OI 

4291.630 

0.054 

0.586 

0.654 

II.  2O 

0.054 

0.585 

0-653 

11.18 

98      AN  INVESTIGATION  OF  THE  ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC   METHODS. 


TABLE  n.  —  RESULTS  FOR  INDIVIDUAL  PLATES.    OBSERVATIONS  OF  1908  —  Continued. 
Plate  w  186.     1908,  Oct.  22,  7''  45m  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  i.o  mm.     Quality,  good. 


C        209.0 

0-n    134-5 

,     P      -25-9 

D  5.1 

Diameter  171.2  mm 

Factor        1.012 


p-P 

o.o 
24.0 

39-7 
86.0 


24-5 
40.0 
86.0 


65.5 

50.0 

4.0 


12.5 
8.1 
5-2 


secy 


1.024 

I.OIO 

1.004 


0  = 

4t° 

</>  = 

4!° 

0  = 

s°!° 

A 

V 

»  +  », 

* 

A 

•o 

II  +  D, 

1 

A 

11 

V  +1>  i 

£ 

4196.699 

0.176 

km 
.920 

km 

2.060 

14.66 

0.176 

km 
1.920 

km 

2.060 

14.66 

0.091 

km 
I.OOO 

km 
1.099 

12.14 

4197-257 

0.176 

.920 

2.060 

14.66 

0.176 

1.920 

2.060 

14.66 

0.092 

I.OIO 

1.109 

12.25 

4203.730 

0.177 

.926 

2.066 

14.70 

0.176 

I.9I5 

2-055 

14.62 

0.092 

I.OIO 

1.109 

12.25 

4207.566 

0.177 

•924 

2.064 

I4-69 

0.177 

1.921 

2.061 

14.67 

0.091 

0.997 

1.096 

12.  IO 

4216.136 

0.177 

.921 

2.061 

14.67 

0.176 

1.909 

2.049 

14-58 

0.093 

•015 

I.II4 

12.30 

4220.509 

0.178 

.928 

2.068 

14.72 

0.177 

1.917 

2.057 

14.64 

0.094 

.021 

.120 

12-37 

4232.887 

0.178 

.919 

2.059 

14.65 

0.178 

1.920 

2.o6o 

14.66 

0.093 

.009 

.108 

12.24 

4233-328 

0.177 

.909 

2.049 

14.58 

0.178 

1.920 

2.060 

14.66 

0.093 

.009 

.108 

12.24 

4257-815 

0.179 

.918 

2-058 

14.65 

0.181 

1.938 

2.078 

14-79 

0.093 

.OO2 

.IOI 

12.  16 

4258.477 

0.179 

1.918 

2.058 

I4-6S 

0.180 

1.928 

2.068 

14-72 

0.093 

.002 

.101 

12.  l6 

4265.418 

0.178 

1.901 

2.041 

I4-52 

0.181 

1.922 

2.062 

14.67 

0.093 

.000 

.099 

12.14 

4266.081 

O.I  80 

1.921 

2.061 

14.67 

0.182 

1.942 

2.082 

14.82 

0.094 

.010 

.109 

12.25 

4268.915 

0.180 

1.920 

2.060 

14.66 

0.180 

1.921 

2.061 

14.67 

0.094 

.009 

.108 

12.24 

4276.836 

0.178 

1.898 

2.038 

I4-5I 

0.179 

1.909 

2.049 

14.58 

0-093 

0.998 

•097 

12.12 

4283.169 

0.180 

1.916 

2.056 

14.63 

0.182 

1.936 

2.076 

14-77 

0.094 

1.005 

.104 

12.19 

4284.838 

0.180 

1.916 

2.056 

14.63 

0.180 

I-9IS 

2-055 

14.62 

0.093 

0-995 

•094 

I  2.  08 

4287.566 

0.179 

1.906 

2.046 

14.56 

0.180 

1.914 

2-054 

14.62 

0.094 

1.005 

.104 

12.19 

4288.310 

0.181 

I-925 

2.065 

14.69 

0.180 

I-9I3 

2-053 

14.61 

0.092 

0.984 

•083 

11.96 

4289.525 

0.179 

1.904 

2.044 

14-55 

0.182 

1-933 

2.073 

14-75 

0.093 

0.994 

•093 

I2.O7 

4290.377 

0.180 

I-9I3 

2-053 

14.61 

0.181 

1.922 

2.062 

14.67 

0.093 

0.994 

•093 

12.07 

4290.542 

0.180 

1.912 

2.052 

14.60 

0.182 

1.932 

2.072 

14-74 

0.094 

1.004 

1.103 

12.18 

4291.630 

0.182 

1.932 

2.072 

'4-74 

0.182 

1.932 

2.072 

14-74 

0.093 

0.994 

1.093 

12.07 

0  = 

65^5 

0  = 

6s!s 

4196.699 

0.052 

0.580 

0.648 

11.09 

0.050 

0-556 

0.624 

10.68 

4197-257 

0.053 

0.590 

0.658 

11.26 

0.050 

0.556 

0.624 

10.68 

4203.730 

0.052 

0.580 

0.648 

11.09 

0.052 

0-577 

0.645 

11.04 

4207.566 

0.052 

0-577 

0.645 

11.04 

0.050 

0-553 

0.621 

10.63 

4216.136 

0.052 

0-575 

0.643 

II.  OI 

0.049 

0.540 

0.608 

10.41 

4220.509 

0.053 

0-585 

0.653 

ii.  18 

0.052 

0-574 

0.642 

10.99 

4232.887 

0.052 

0-573 

0.641 

10.97 

0.052 

0-572 

0.640 

10.96 

4233-328 

0-053 

0-583 

0.651 

11.14 

0.052 

0.572 

0.640 

10.96 

4257-815 

0.054 

0.590 

0.658 

11.26 

0.052 

0.566 

0.634 

10.85 

4258.477 

0.053 

0.580 

0.648 

11.09 

0.051 

0-555 

0.623 

10.66 

4265.418 

0.054 

0.589 

0.657 

11.25 

0.051 

0-554 

0.622 

10.65 

4266.081 

0.054 

0.589 

0.657 

11.25 

0.052 

0-565 

0-633 

10.84 

4268.915 

0.054 

0.588 

0.656 

11.23 

0.052 

0-565 

0.633 

10.84 

4276.836 

0.054 

0.587 

0-655 

II.  21 

0.052 

0.564 

0.632 

10.82 

4283.169 

0.052 

0.566 

0.634 

10.85 

0.052 

0.562 

0.630 

10.78 

4284.838 

0.054 

0.586 

0.654 

1  1.  2O 

0.052 

0.562 

0.630 

10.78 

4287.566 

0.054 

0.585 

0-653 

II.I8 

0.050 

0-544 

0.6  1  2 

10.48 

4288.310 

0-055 

0.596 

0.664 

"•37 

0.052 

0.562 

0.630 

10.78 

4289.525 

0.053 

0-575 

0.643 

II.OI 

0.052 

0.561 

0.629 

10.77 

4290.377 

0.054 

0-585 

0-653 

ii.  18 

0.051 

o.SSO 

0.618 

10.58 

4290.542 

0.052 

0-565 

0.633 

10.84 

0.052 

0.561 

0.629 

10.77 

4291.630 

0.053 

0-575 

0.643 

II.OI 

0.051 

0-550 

0.618 

10.58 

MEAN   RESULTS   FOR   EACH   PLATE   FROM   ALL   LINES.      OBSERVATIONS    OF    1908. 


99 


The  results  for  the  individual  plates  are  summarized  in  Tables  12,  13,  and  14,  which  are  identical  in 
form  with  Tables  5,  6,  and  7  for  the  1906-1907  observations. 

TABLE  12. —  MEAN  RESULTS  FOR  EACH  PLATE  FROM  ALL  LINES.    OBSERVATIONS  OF  1908. 


PLATE 
No. 

DATE. 

No.  OF 
LINES. 

0 

i  +  »j 

f 

PLATE 

No. 

DATE. 

No.  OF 
LINES. 

0 

»  +  », 

£ 

1908 

0 

km 

o 

1908 

o 

km 

0 

<a  103 

Feb.  16 

22 

—  0.2 

2.071 

14.71 

w  n7l 

May  26 

22 

-0.6 

2.056 

14.60 

I4.I 

1.948 

14.26 

14.4 

1.895 

13.89 

29.9 

I.63S 

13-39 

29.4 

1.664 

13-56 

44.8 

1.289 

12.89 

44-6 

1.301 

12.98 

59-5 

0.774 

10.83 

60.4 

0-837 

12.03 

73-7 

°-439 

II.  II 

75-9 

0-372 

10.84 

w  105, 

Mar.  10 

22 

-o-3 

2.057 

14.60 

<"  "72 

May  26 

22 

-0.6 

2.058 

14.61 

14.6 

1.989 

14-59 

14.4 

1.898 

13-91 

29.4 

1.634 

I3-3I 

29-4 

1.664 

13-57 

44.2 

1.346 

13-33 

44-6 

1.298 

12-95 

59-3 

0.847 

11.77 

60.4 

0.845 

12.15 

74-3 

0.419 

11.00 

75-9 

0.385 

11.22 

a  105, 

Mar.  10 

22 

-0-3 

2.081 

14-77 

W  I20J 

June  2 

22 

2-3 

2.053 

I4-58 

14.6 

1.971 

14-47 

12.7 

1-959 

14.25 

29.4 

1.662 

13-54 

17-3 

1.862 

13.86 

44-2 

1-342 

13.29 

32-8 

1.645 

13.89 

59-3 

0.840 

11.68 

48-3 

I-I75 

12-54 

74-3 

0.401 

10.51 

63-8 

0.640 

IO.29 

77-3 

0-335 

10.82 

u  105., 

Mar.  10 

22 

-0.4 

2.072 

14.72 

<0  I202 

June  2 

22 

4-3 

2.042 

14-54 

-0.4 

2.070 

14.71 

10.7 

2.009 

I4.5I 

15-2 

1.956 

14-39 

19-3 

1.840 

13.86 

3°-  1 

1-675 

13-75 

34-8 

1.610 

13.92 

50-3 

i-i59 

13.88 

65-3 

0.693 

I2.O4 

79-3 

0.259 

9.91 

w  i°52 

Mar.  10 

22 

-0.4 

2.080 

14-77 

w  128 

June  9 

22 

-o-S 

2.057 

14.61 

-0.4 

2.073 

14.72 

14-5 

1.917 

14.06 

15-2 

1.966 

14-45 

29-5 

1.687 

I3.76 

30.1 

1.669 

I3-7I 

44-5 

1.260 

12.54 

59-5 

0.832 

11.64 

74-5 

0.380 

IO.I2 

w  106 

Mar.  10 

22 

45-i 

1.312 

13.20 

a  132 

June  10 

22 

4-4 

2.032 

14.47 

60.4 

0.792 

11.38 

19.4 

1.897 

14.28 

75-1 

0.416 

11.49 

34-4 

1-593 

13-73 

49-4 

1.169 

12.75 

64.4 

0.715 

n-75 

79-4 

0.262 

10.12 

w  106 

Mar.  10 

22 

45-i 

1.293 

13.01 

u  134 

June  ii 

22 

-o.S 

2.043 

I4-5I 

60.4 

0.747 

10.80 

4-5 

2.013 

14-54 

7S-i 

0.407 

11.24 

19-5 

1.859 

I4.OO 

75-i 

0.407 

11.24 

34-5 

1-557 

I3-42 

60.4 

0.797 

11.44 

49-5 

1.165 

12.74 

45-i 

1.302 

13.10 

64-5 

0.707 

11.66 

30.1 

1.658 

13.61 

79-5 

0.262 

10.22 

15-2 

1.971 

I4-5I 

a  113 

Apr.  8 

22 

o.o 

2.IOO 

14.92 

<*  135, 

June  ii 

22 

-0-5 

2.064 

14.66 

14.9 

1.969 

14.46 

14-5 

1.940 

14.22 

29.8 

1.679 

13-75 

29-5 

1.676 

I3-67 

44.8 

1.298 

12.98 

44-5 

'•245 

12-39 

60.7 

0.801 

11.62 

59-5 

0.772 

10.80 

75-7 

0.360 

10.36 

74-5 

0.381 

10.12 

79-5 

0.262 

10.22 

w  113 

Apr.  8 

22 

o.o 

2.081 

14-77 

<"I352 

June  ii 

22 

-0-5 

2.038 

14.46 

14.9 

1.961 

14.41 

14-5 

1.938 

14.21 

29.8 

1.682 

I3-76 

29-5 

i.  68  1 

I3-72 

44-8 

1.294 

12-94 

44-5 

1-237 

12.31 

60.7 

Q-793 

11.52 

59-5 

0.772 

10.79 

75-7 

0.363 

10.45 

74-5 

0.384 

10.21 

79-5 

0.260 

10.12 

IOO     AN  INVESTIGATION  OF   THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 
TABLE  12. —  MEAN  RESULTS  FOR  EACH  PLATE  FROM  ALL  LINES.    OBSERVATIONS  OF  1908  —  Continued. 


PLATE 

No. 

DATE. 

No.  OF 

LINES. 

</> 

V  +  V1 

{ 

PLATE 
No. 

DATE. 

No.  or 
LINES. 

<t> 

»  +  r, 

1 

1908 

0 

km 

0 

1908 

0 

km 

0 

u  136 

June  ii 

22 

-o-S 

2.047 

14-53 

u  165 

Aug.  27 

22 

4-2 

2.032 

14.47 

4-5 

1.981 

14.11 

n.6 

1.992 

14-43 

I9-S 

1.847 

13-91 

19.1 

1.  880 

14.12 

34-5 

i-5Si 

13-36 

34-1 

1-557 

13-35 

49-5 

1.158 

12.66 

49-4 

1.142 

12.46 

64-S 

0.656 

10.81 

64.8 

0.688 

11.48 

79-5 

0.266 

10.36 

w  146 

Aug.  S 

22 

0-3 

2.028 

14.40 

w  166 

Aug.  27 

22 

4-2 

2.049 

14.58 

15-2 

1-934 

14-23 

n.6 

1.984 

I4.38 

30.1 

1.658 

13.60 

19.1 

1.874 

14.07 

45-5 

1.265 

12.  8l 

34-1 

1.561 

I3-38 

60.7 

0.682 

10.97 

49-4 

1.150 

12-55 

75-4 

0.405 

"•35 

64.8 

0.691 

11.52 

u  147 

Aug.  5 

22 

0-3 

2.052 

14-57 

w  179 

Sept.  30 

22 

60.  1 

0.865 

12.32 

15-2 

1-959 

14.42 

60.  1 

0.867 

12-35 

30.1 

1.686 

13-85 

45-5 

1.269 

12.86 

60.7 

0.781 

"•34 

75-4 

0.401 

11.30 

w  148 

Aug.  5 

22 

°-3 

2.056 

14.60 

w  180 

Sept.  30 

22 

60.  1 

0.808 

11.51 

15-2 

1-959 

14.41 

60.  1 

0.810 

"•S3 

30-1 

1.688 

13-85 

35-5 

1.265 

12.81 

60.7 

0.798 

"•59 

754 

0.403 

11.36 

<">  151 

Aug.  6 

22 

-o-3 

2.062 

14.64 

<•>  182 

Oct.  9 

22 

II.O 

1.990 

14-39 

-0-3 

2.060 

14-63 

II.O 

1.992 

14.40 

14.6 

1-952 

14-32 

19.0 

1.843 

13-84 

44.6 

1.270 

12.66 

33-9 

1.483 

12.69 

59-8 

0.809 

11.42 

74-9 

0.415 

11.31 

<»  161 

Aug.  26 

22 

4-2 

2.044 

14-55 

<•>  183 

Oct.  9 

22 

II.O 

1.991 

14.40 

10.9 

1.989 

14.38 

II.O 

1.997 

14.44 

19.1 

1.886 

14.18 

19.0 

1.864 

14.00 

34-2 

1-547 

13.27 

19.0 

1.858 

13-95 

49-4 

1.080 

11.78 

19.0 

1.859 

13.96 

65.0 

0.631 

10.60 

33-9 

1-549 

13-25 

33-9 

1-55° 

13.26 

33-9 

1.546 

13-22 

ta  162 

Aug.  26 

22 

4-2 

2.048 

14-57 

u  184 

Oct.   22 

22 

4-° 

2.059 

14.65 

10.9 

1.986 

14-36 

50.0 

1.115 

12.31 

19.1 

1.878 

14.11 

50.0 

1.128 

12.46 

34-2 

i-5°5 

12.91 

60.3 

0.823 

11.79 

49-4 

1.144 

12.48 

60.3 

0.827 

11.85 

65.0 

0.693 

11.67 

65-5 

0.668 

11.46 

65-5 

0.663 

"•37 

o>  163 

Aug.  26 

22 

4-2 

2.040 

14-52 

w  185 

Oct.  22 

22 

4.0 

2.060 

14.66 

10.9 

2.002 

14.46 

50.0 

1.103 

12.18 

19.1 

1.886 

14.18 

50.0 

1.105 

12.21 

34.2 

1.548 

13.29 

65-5 

0.652 

11.17 

49-4 

1.149 

12.54 

65-5 

0.647 

II.08 

65.0 

0.688 

"•55 

u  164 

Aug.  26 

22 

4.2 

2.029 

14.44 

w  186 

Oct.   22 

22 

4.0 

2.057 

14.64 

10.9 

1-995 

14.42 

4-0 

2.063 

14.68 

19.1 

1.870 

14.06 

50.0 

I.IOI 

12.17 

34-2 

1.556 

13-36 

65.5 

0.650 

11.14 

2O 

49-4 

1.152 

12.56 

65-5 

0.628 

iQ-75 

20 

65.0 

0.700 

11.76 

MEAN   RESULTS   FOR   EACH   LATITUDE   FROM   ALL    LINES.      OBSERVATIONS   OF    1908. 
TABLE  13.  —  MEAN  RESULTS  FOR  EACH  LATITUDE  FROM  ALL  LINES.    OBSERVATIONS  OF  1908. 


IOI 


PLATE 

No. 

<t> 

»  +  »! 

f 

PLATE 
No. 

0 

v  +  v1 

£ 

PLATE 
No. 

0 

s  +  r, 

£ 

PLATE 
No. 

<t> 

»  +  »! 

£ 

u  103 

i°5i 
io5i 

ios2 
i°52 

I052 

i°52 
"3 
"3i 
«7i 

U?2 
128 

134 

I35i 
i352 
136 
146 

147 
148 

151 
IS' 

O.2 

°-3 
°-3 

0.4 
0.4 
0.4 
0.4 

0.0 
0.0 

0.6 

0.6 

°-5 
0-5 
o-S 
o-S 
o-S 
°-3 
°-3 
°-3 
°-3 
o-3 

km 

2.071 
2.057 
2.081 
2.072 
2.070 
2.080 
2.073 

2.100 
2.081 
2.056 
2.058 
2.057 
2.043 
2.064 
2.038 
2.047 
2.028 
2.O52 
2.056 
2.062 
2.o6o 

14.71 
14.60 

H-77 
14.72 
14.71 

14-77 
14.72 
14.92 

14-77 
14.60 
14.61 
14.61 

14-51 
14.66 
14.46 

14-53 
14.40 

14-57 
14.60 
14.64 
14.63 

<*  103 

105! 

i05i 
i°52 
io52 
106 

"3 
"3 
"7i 
"72 

I20t 
128 

i3Si 

i352 
146 

H7 
148 

151 

14.1 
14.6 
14.6 

15-2 

IS-2 
15-2 
14.9 
14.9 
14.4 
14.4 
17-3 

14-5 
14-5 
14-5 
iS-2 
15-2 
iS-2 
14.6 

km 
1.948 
1.989 
1.971 

•956 
.966 
.971 
.969 
.961 

.895 
.898 
.862 
.917 
.940 
.938 
•934 
•959 
•959 
•952 

14.26 

J4-59 
14.47 

14-39 
14-45 
14-51 
14.46 
14.41 
13.89 
13-91 
13-86 
14.06 
14.22 
14.21 

14-23 
14.42 
14.42 
14-32 

W  I2O[ 
I2O] 

132 
134 
136 

161 
162 
163 
164 
165 
166 
182 
183 
183 
183 

32.8 
34-8 
34-4 
34-5 
34-5 
34-2 
34-2 
34-2 
34-2 
34-1 
34-1 
33-9 
33-9 
33-9 
33-9 

km 

•645 
.610 

•593 
•557 
•551 
1-547 
i-5°5 
1.548 
I-556 
1-557 
1.561 
1.483 
1-549 
i-SSO 
1.546 

0 

13.89 
13-92 
13-73 
13-42 
12.36 

13-27 
12.91 

13-29 
13-36 
13-37 
13-38 
12.69 

13-25 
13.26 
13-22 

<a  103 
I05i 

105! 

1  06 
106 
1  06 
"3 
"3 
"7i 
ii72 
128 
I35i 
I352 
146 

147 
148 

151 
179 
1  80 
i  So 
184 
184 

0 

59-5 
59-3 
59-3 
60.4 
60.4 
60.4 
60.7 
60.7 
60.4 
60.4 
59-5 
59-5 
59-5 
60.7 
60.7 
60.7 
59-8 
60.  i 
60.  i 
60.  i 
60.3 
60.3 

km 

0.774 
0.847 
0.840 
0.792 

0-747 
0.797 
0.801 

0-793 
0-837 
0.845 
0.832 
0.772 
0.772 

0-755 
0.781 
0.798 
0.809 
0.866 
0.808 
0.810 
0.823 
0.827 

o 

10.83 
11.77 
11.68 
11.38 
10.80 
11.44 
11.62 
11.52 
12.03 
12.15 
11.64 
10.80 
10.79 
10.97 
H-34 
"•59 
11.42 

12.34 
11.51 

"•53 
11.79 
11.85 

Means,     34.1       1.557      13-35 

Means,     14.9      1.944      14.28 

Means,      0.4      2.062      14.64 

Means,     60.1      0.801       11.49 

W  120! 
I202 

132 
134 
136 
161 
162 
163 
164 

165 
166 
184 
184 
185 
185 
1  86 
1  86 

63-8 
65-3 
64-4 
64-5 
64-5 
65.0 
65.0 
65.0 
65-0 
64.8 
64.8 
65-5 
65-5 
65-5 
65-5 
65-5 
65-5 

0.640 
0.693 

0-715 
0.707 
0.656 
0.631 
0.693 
0.688 
0.700 
0.688 
0.691 
0.668 
0.663 
0.652 
0.647 
0.650 
0.628 

10.29 
12.04 

"•75 
11.66 
10.81 
10.60 
11.67 

"•55 
11.76 
11.48 
11.52 
11.46 

"•37 
11.17 
11.08 
11.14 

10.75 

W   I  2O, 
I2Oj 

132 
134 
136 
161 
162 
163 
164 

165 
1  66 
184 
185 
1  86 
1  86 

2-3 

4-3 
4-4 
4-5 
4-5 
4-2 
4-2 
4.2 
4-2 
4-2 
4-2 
4.0 
4-0 
4.0 
4.0 

2-OS3 
2.042 
2.032 
2.013 
1.981 
2.044 
2.048 
2.040 
2.  02Q 
2.032 
2.049 
2.059 
2.O6O 
2.057 
2.063 

14-58 
14-54 
14-47 
14-54 
14.11 

'4-55 
14-57 
14-52 
14-44 
14.47 
14-58 
14-65 
14.66 
14.64 
14.68 

W  I2O2 

132 
134 
136 
161 
162 
163 
164 

165 
166 
182 
183 
183 
183 

19-3 
19.4 

19-5 
19-5 
19. 
19. 
19. 
19. 
19. 
19.1 
19.0 
19.0 
19.0 

IO.O 

.840 
.897 
-859 
•847 
.866 
.878 
.886 
.870 
.880 
.874 

•843 
.864 
•858 
1.859 

13-86 
14.28 
14.00 

13-91 
14.18 
14.11 
14.18 
14.06 
14.12 
14.07 

13-84 
14.00 

13-95 
13.96 

w  103 
105, 

io5i 
1  06 
106 
106 
"3 
"3 
"7t 
117, 
128 
i3Si 
i352 
146 

147 
148 
151 

44-8 
44-2 
44.2 

45-i 
45-i 
45-1 
44.8 
44.8 
44-6 
44-6 
44-5 
44-5 
44-5 
45-5 
45-5 
45-5 
45-6 

1.289 
1.346 
1-342 
1.312 

1-293 
1.302 
1.298 
1.294 
1.301 
1.298 
1.260 
i  -245 
1-237 
1.265 
1.269 
1.265 
1.270 

12.89 

13-33 
13.29 
13.20 
13.01 
13.10 
12.98 
12.94 
12.98 
".95 
12.54 
12.39 
12.31 
12.81 
12.86 
12.81 
12.66 

Means,     65.0      0.671       11.30 

Means,     19.2      1.867       !4-°4 

w  103 
ioSi 
io5i 
106 
106 
106 
"3 
"3 

"?! 
"72 
128 
'35i 
1352 
146 

147 

148 

151 

73-7 
74-3 
74-3 
75-i 
7S-i 
75-1 
75-7 
75-7 
75-9 
75-9 
74-5 
74-5 
74-5 
75-4 
75-4 
75-4 
74-9 

0-439 
0.419 
0.401 
0.416 
0.407 
0.407 
0.360 

0-363 
0.372 

0.385 
0.380 
0.381 
0.384 
0.405 
0.401 
0.403 
0.415 

ii.  ii 

II.OO 

10.51 
11.49 
11.24 
11.24 
10.36 

10.45 
10.84 

11.22 
IO.I2 
10.12 
IO.2I 

"•35 
11.30 
11.36 
11.31 

Means,       4.1       2.040       14.53 

Means,     44.8      1.289       12.88 

w  I2Oi 
I202 

161 
162 

163 
164 

165 
166 
182 
182 
183 
183 

12.7 
10.7 
10.9 
10.9 
10.9 
10.9 
n.6 
1  1.6 

II.O 

II.O 
II.O 

I  1.0 

i  -959 
2.009 
1.989 
1.986 

2.OO2 

i  -995 
1.992 
1.984 
1.990 
1.992 
1.991 
1.997 

14-25 
U-Si 
14.38 
14-36 
14.46 
14.42 
14-43 
14-38 
14-39 
14.40 
14.40 
14.44 

w  103 
ioSi 
105, 
ios2 
ios2 
106 
"3 
"3 
"7i 
H72 
128 
I35i 
I352 
146 

147 
148 

29.9 
29.4 
29.4 
30.1 
30.1 
30.1 
29.8 
29.8 
29.4 
29-4 
29-5 
29-5 
29-5 
30.1 
30.1 
30.1 

1-635 
1.634 
1.662 

I-675 
1.669 
1.658 
1.679 
1.682 
1.664 
1.664 
1.687 
1.676 
1.681 
1.658 
1.686 
1.688 

13-39 
13-31 
13-54 
13-75 
13-71 
13.61 

13-75 
13-76 
13-56 
'3-57 
13-76 
13-67 
I3-72 
13.60 
13-85 
13-85 

ia  i20i 

I2O2 

132 
134 
136 
161 
162 
163 
164 
165 
166 
184 
184 
185 
185 
1  86 

48-3 
50-3 
49-4 
49-5 
49-5 
49-4 
49-4 
49.4 

49-4 
49-4 
49.4 
50.0 
50.0 
50.0 
50.0 
50.0 

I-I7S 
1-159 
.169 
.165 
.158 
.080 
•  144 
-149 
•152 
.142 
.150 

•"5 
.128 
.103 
-105 

.IOI 

12.54 
12.88 

12.75 
12.74 
12.66 
11.78 
12.48 
12.54 
12.56 
12.46 

12.55 
12.31 
12.46 
12.18 

12.21 

12.17 

Means,     75.0      0.396      10.86 

«)   I2Ol 
1202 

132 
134 
1351 
1352 

136 

77-3 
79-3 
79-4 
79-5 
79-5 
79-5 
79-5 

0-335 
0-259 
0.262 
0.262 
0.262 
0.260 
0.266 

10.82 
9.91 

IO.I2 
IO.22 
10.22 
I  O.I  2 
10.36 

Means,  _  11.2      1-990      14.40 

Means,     29.8      1.669      T3-65 

Means,     49.6      1.137       12.45 

Means,     79.1      0.272      10.25 

102      AN  INVESTIGATION   OF   THE  ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  14. — MEAN  RESULTS  FOR  EACH  LINE  FROM  ALL  PLATES.    OBSERVATIONS  OF  1908. 


0  =  o!4 

0  =  4?i 

0=^2 

0  =  .4!0 

X 

ELEMENT. 

No.  OF 

No.  OF 

« 

No.  OF 

No.  OF 

« 

PLATES. 

s  +  », 

£ 

PLATES. 

!>  +  », 

PLATES. 

+     ! 

PLATES. 

+   » 

km 

0 

km 

o 

km 

o 

km 

° 

4196.699 

La 

21 

2.034 

14.44 

15 

2.023 

14.40 

12 

1.979 

14-31 

18 

1.925 

14.14 

4197-257 

CN 

21 

2.047 

14-53 

15 

2.028 

14 

43 

12 

1.978 

14-31 

18 

1.927 

14.16 

4203-730 

Cr 

21 

2.061 

14.63 

IS 

2-034 

14.48 

12 

1.992 

14.42 

18 

1-944 

14.28 

4207.566 

CN 

21 

2.054 

14.58 

15 

2.038 

14 

50 

12 

1.989 

14-39 

18 

1-937 

14-23 

4216.136 

CN 

21 

2.042 

14.49 

15 

2.031 

14.46 

12 

1.983 

14-34 

18 

1.930 

14.18 

4220.509 

Fc 

21 

2.059 

14.62 

15 

2.052 

14.61 

12 

1.998 

14-45 

18 

1-945 

14.29 

4232.887 

Fe 

21 

2.066 

14.67 

15 

2.048 

14 

58 

12 

1.992 

•  14-41 

18 

1.948 

14.31 

4233-328 

Mn 

21 

2-055 

14-59 

15 

2.052 

14 

61 

12 

1-995 

14.43 

18 

1-945 

14.29 

4257-8I5 

Mn 

21 

2.077 

14-75 

15 

2.049 

14 

58 

12 

1.998 

14-45 

18 

1-953 

14.34 

4258.477 

Fe 

21 

2.068 

14.68 

15 

2.046 

14 

56 

12 

1.998 

14-45 

18          1-952 

14-34 

4265.418 

Fe 

21 

2.060 

14.62 

15 

2.042 

14-53 

12 

1-993 

14.41 

1  8          1.946 

14.30 

4266.081 

Mn 

21 

2-073 

14.72 

15 

2.051 

14 

60 

12 

1.997 

14.44 

1  8          1.946 

14-30 

4268.915 

Fe 

21 

2.073 

14.72 

15 

2-045 

14 

56 

12 

1-994 

14.42 

18 

1-949 

14.32 

4276.836 

-Zr 

21 

2.067 

14.68 

15 

2.037 

14.50 

12 

1.986 

14.36 

18 

1.948 

14-31 

4283.169 

Ca 

21 

2.066 

14.67 

15 

2.039 

I4-5I 

12 

1.991 

14.40 

18 

1.948 

14-31 

4284.838 

Ni 

21 

2.069 

14.69 

IS 

2.040 

14 

52 

12 

1.988 

14.38 

18 

1.936 

14.22 

4287.566 

Ti 

21 

2.066 

14.67 

IS 

2.036 

14.49 

12 

1.988 

14.38 

18 

1.944 

14.28 

4288.310 

Ti,  Fe 

21 

2.064 

14.65 

IS 

2.036 

14-49 

12 

1.990 

14-39 

18 

1.949 

14-32 

4289.525 

Ca 

21 

2.069 

14.69 

15 

2.040 

14.52 

12 

1.992 

14.41 

18 

1.950 

14-33 

4290-377 

Ti 

21 

2.059 

14.62 

15 

2-034 

14.48 

12 

1.986 

14.36 

18 

1.938 

14.24 

4290.542 

Fe 

21 

2.068 

14.68 

IS 

2.040 

14.52 

12 

1-994 

14.42 

18 

1-953 

14-35 

4291.630 

Fe 

21 

2.071 

14.70 

15 

2.041 

14-53 

12 

1.992 

14.41 

18 

1-947 

14-30 

X 

ELEMENT. 

0  =  I9t2 

0  =  29^8 

0  =  34?i 

0  =  44?8 

4196.699 

La 

14 

1.859 

13.98 

1  6 

1.652 

13 

52 

15 

1.546 

13.26 

I? 

1.275 

12-75 

4197-257 

CN 

14 

1.859 

13.98 

16 

I.655 

13 

54 

15 

1-544 

13.24 

I? 

1.280 

12.80 

4203.730 

Cr 

H 

1.871 

14.06 

16 

1.671 

13 

67 

15 

1.561 

13.38 

17 

.288 

12.88 

4207.566 

CN 

14 

1.875 

14.10 

16 

1.667 

13 

64 

15 

1.560 

13.37 

17 

-283 

12.83 

4216.136 

CN 

14 

1.862 

14.00 

16 

1.647 

13-47 

15 

1.548 

13.27 

I? 

.272 

12.72 

4220.509 

Fc 

14 

1.874 

14.09 

16 

1.671 

13 

67 

15 

1.561 

13-38 

I? 

.288 

12.88 

4232-887 

Fe 

14 

1.875 

14.10 

16 

1.669 

I3-65 

15 

1-559 

13-37 

17 

.282 

12.82 

4233-328 

Mn 

14 

1.878 

14.12 

16 

1.662 

13.60 

15 

1.561 

13-38 

I? 

.287 

12.87 

4257-8i5 

Mn 

14 

1.876 

14.10 

16 

.676 

13 

7i 

15 

1-567 

13-43 

I? 

.300 

13.00 

4258.477 

Fe 

14 

1.871 

14.06 

16 

-677 

13 

72 

15 

1.560 

13-37 

I? 

•  294 

12.94 

4265.418 

Fe 

H 

I.86I 

13-99 

16 

.666 

13-63 

15 

1-555 

13-33 

I? 

.284 

12.84 

4266.081 

Mn 

14 

1-873 

14.08 

16 

.672 

13.68 

15 

1.561 

13-38 

I? 

.297 

12.97 

4268.915 

Fe 

14 

I. 

869 

14.05 

16 

.673 

13.69 

15 

1-559 

13-37 

I? 

.292 

12.92 

4276.836 

-Zr 

H 

I. 

864 

14.02 

16 

.673 

13-69 

15 

1-554 

13-32 

17 

.284 

12.84 

4283.169 

Ca 

14 

I. 

866 

14.03 

16 

.672 

13.68 

15 

1-553 

13.32 

I? 

.287 

12.87 

4284.838 

Ni 

14 

I. 

860 

13.98 

16 

.657 

I3-56 

IS 

1-557 

13-31 

17 

.282 

12.82 

4287.566 

Ti 

14 

I. 

862 

14.00 

16 

.671 

13-67 

IS 

1-554 

13.32 

i? 

.292 

12.92 

4288.310 

Ti,  Fe 

14 

I. 

865 

14.02 

16 

-675 

I3-70 

15 

1.560 

13.37 

i? 

.291 

12.91 

4289.525 

Ca 

14 

I. 

861 

13-99 

16 

.676 

13-71 

15 

1-558 

13-36 

i? 

•297 

12.97 

4290.37? 

Ti 

14 

I. 

858 

13-97 

16 

.666 

13 

63 

15 

1-557 

13-36 

i? 

.278 

12.78 

4290.542 

Fe 

14 

I. 

869 

14.05 

16 

•683 

13 

77 

IS 

1-565 

13-42 

i? 

.294 

12.94 

4291-630 

Fe 

14 

I. 

871 

14.06 

16 

.680 

13 

74 

IS 

1.562 

13-39 

i? 

•  294 

12.94 

0  =  49^6 

0   =   6O°  I 

0  =  65^0 

0  =  75!o 

0  =  79^1 

X 

ELEMENT. 

"Jo.OF 

> 

No.  OF 

V 

No.  OF 

No.  OF 

No.  OF        , 

£ 

1 

'LATES. 

+   ' 

£ 

PLATES 

»+*, 

? 

PLATES. 

»  +  », 

* 

PLATES. 

»  +  », 

£ 

? 

km 

o 

km 

0 

km 

0 

km  ' 

0 

km 

° 

4196.699 

La 

16 

•125 

12.32 

22 

0.791 

11.26 

17 

0.658 

11.05 

17 

0.380 

10.42 

7         0.267 

IO.O2 

4197-257 

CN 

16 

.125 

12.32 

22 

0.791 

11.26 

17 

0.663 

11.14 

17 

0.385 

10.56 

7        0.269 

IO.IO 

4203-730 

Cr 

16 

.138 

12.46 

22 

0.805 

11.46 

17 

0.670 

11.26 

i? 

0.392 

10.75 

7        0.269 

IO.IO 

4207.566 

CN 

16 

.138 

12.46 

22 

0.804 

"•45 

17 

0.666 

11.19 

17 

0.388 

10.65 

7        0.270 

10.14 

4216.136 

CN 

16 

.130 

12.38 

22 

0.796 

"•34 

!7 

0.659 

11.07 

0.386 

10.59 

7        0.261 

9.80 

4220.509 

Fe 

16 

.144 

12.53 

22 

0.805 

11.46 

17 

0.671 

11.27 

i? 

0.400 

10.97 

7       0.267 

IO.O2 

4232-887 

Fe 

16 

-138 

12.46 

22 

0.801 

11.41 

0.671 

11.27 

17 

0-397 

10.89 

7        0.266 

9-99 

4233-328 

Mn 

16 

•139 

12.48 

22 

0.805 

11.46 

17 

0.671 

11.27 

17 

0.386 

10.59 

7        0.269 

IO.IO 

4257.815 

Mn 

15 

•    .142 

12.51 

22 

0.8  1  6 

11.62 

16 

0.675 

"•34 

17 

0.406 

11.14 

7        0.281 

^0.55 

4258.477 

Fe 

15 

.138 

12.46 

22 

0.807 

11.49 

16 

0.672 

11.29 

17 

0-399 

10.94 

7        0.267 

10.02 

4265.418 

Fe 

16 

•134 

12.42 

22 

0.807 

11.49 

i? 

0.672 

11.29 

17 

0-397 

10.89 

7       0.277 

10.40 

4266.081 

Mn 

16 

.141 

12.50 

22 

0.805 

11.46 

17 

0.676 

11.36 

17 

0.402 

11.03 

7        0.282 

10.59 

4268.915 

Fe 

16 

•139 

12.48 

22 

0.811 

"•55 

17 

0.482 

11.46 

17 

0.404 

11.08 

7        0.277 

10.40 

4276.836 

-Zr 

16 

.136 

12.44 

22 

0.812 

11.56 

17 

0.674 

11.32 

17 

0.402 

11.03 

7        0.276 

10.36 

4283.169 

Ca 

16 

•139 

12.48 

22 

0.811 

"•55 

i? 

0.672 

11.29 

17 

0.398 

10.91 

7        0.274 

10.29 

4284.838 

Ni 

16 

•137 

12.45 

22 

0.807 

11.49 

i? 

0.673 

11.31 

0.406 

11.14 

7       0.270 

10.14 

4287-566 

Ti 

16 

-134 

12.42 

22 

0.810 

"•54 

17 

0.670 

11.26 

i? 

0.400 

10.97 

7       0.274 

10.29 

4288.310 

Ti,  Fe 

16 

.140 

12.49 

22 

0.810 

"•54 

17 

0.674 

11.32 

17 

0-399 

10.94 

7        0.281 

10.55 

4289.525 

Ca 

16 

.144 

12.53 

22 

0.808 

11.51 

0.679 

11.41 

17 

0-399 

10.94 

7       0.279 

10.47 

4290.377 

Ti 

16 

•132 

12.40 

22 

0.800 

"•39 

17 

0.669 

11.24 

17 

0.392 

10.75 

7       0.270 

10.14 

4290.542 

Fe 

16 

.141 

12.50 

22 

0.812 

11.56 

17 

0.677 

"•37 

17 

0.402 

11.03 

7        0.270 

10.14 

4291.630      Fc 

16 

.144 

12.53 

22 

0.813 

".58 

17 

0.676 

11.36 

17 

0.400 

10.97 

7        0.278 

10.44 

ADAMS 


PLATE   2 


OBSERVATIONS  ON  HYDROGEN.  103 

9.  SPECIAL  OBSERVATIONS  ON  THE  a  LINE  OF  HYDROGEN. 

As  will  be  seen  when  we  reach  the  discussion  of  the  results  for  the  individual  lines  of  the  reversing  layer 
on  page  lOQof  this  investigation,  the  observations  of  1906-1907  and  of  1908  agree  in  indicating  that  different 
lines  give  different  velocities  of  rotation.  Since  this  result  clearly  is  connected  with  the  level  at  which  the 
lines  originate  in  the  sun's  atmosphere,  an  investigation  of  the  lines  of  the  elements  which  show  great  dif- 
ferences of  level  becomes  of  much  interest.  The  two  elements  which  appear  to  rise  to  the  greatest  height 
above  the  solar  photosphere,  as  indicated  by  observations  of  the  chromospheric  spectrum,  are  calcium  and 
hydrogen.  Unfortunately,  accurate  measures  of  the  H  and  K  lines  of  calcium  at  the  sun's  limb  are  very 
difficult,  on  account  of  the  great  variation  in  their  width  and  appearance  and  the  presence  of  bright 
reversals.  Exclusive  of  these  lines,  the  blue  line  of  calcium  at  A.  4227,  which  represents  a  considerably  lower 
level  than  H  and  K,  remains.  Among  the  hydrogen  lines,  H8  and  Hf3  are  practically  ruled  out  on  account 
of  the  presence  of  foreign  lines,  and  Hy  is  rendered  unsymmetrical  by  the  same  cause.  Accordingly,  in  the 
selection  of  lines  for  measurement  only  Ha  was  left.  The  investigation  of  this  line  became  of  interest  for 
several  other  reasons.  Photographs  of  the  spectra  of  the  center  and  limb  of  the  sun  indicated  that  Ha 
was  greatly  widened  at  the  limb,  while  the  other  hydrogen  lines,  with  the  possible  exception  of  H@,  were 
either  unchanged  or  slightly  narrowed.  The  line  also  showed  no  such  displacement  toward  the  red  at  the 
sun's  limb  as  was  found  for  essentially  all  of  the  lines  in  the  solar  spectrum.  Moreover,  plates  taken  with 
the  spectroheliograph  with  the  a  line  showed  structure  differing  in  many  respects  from  that  obtained 
through  the  other  hydrogen  lines.  All  of  these  results  are  in  harmony  with  the  chromospheric  observations 
in  indicating  a  very  high  level  for  the  hydrogen  gas  which  produces  Ha  in  the  sun's  atmosphere. 

The  measurement  of  the  center  and  limb  plates  soon  showed  that  the  Ha  line  would  give  abnormally 
high  rotational  velocities,  and  the  first  photographs  taken  with  the  regular  rotation  apparatus  confirmed 
this  result.  A  few  preliminary  results  of  this  investigation  were  published  early  in  1908  (15),  but  a  much 
more  extensive  series  of  plates  was  obtained  during  the  spring  of  that  year.  The  use  of  fine-grained  plates 
sensitized  to  the  red  by  the  use  of  Wallace's  formula  proved  of  the  greatest  value  in  the  investigation,  since 
the  edges  of  the  line  are  so  hazy  as  to  make  the  superior  defining  power  of  these  plates,  and  their  excellent 
contrast,  of  much  assistance  in  the  measurement.  All  of  the  results  given  were  obtained  from  plates  of  this 
character. 

It  is  of  course  hardly  necessary  to  state  that  the  degree  of  accuracy  attained  in  the  measurement  of 
Ha  is  of  quite  another  order  from  that  for  the  narrow  lines  of  the  reversing  layer.  The  width  of  Ha  at  the 
sun's  limb  is  about  1.15  Angstroms,  as  against  0.15  Angstrom  for  the  lines  employed  in  the  reversing  layer. 
Moreover,  all  of  the  plates  used  for  measurement  were  taken  in  the  spectrum  of  the  second  order,  thus  giv- 
ing a  linear  scale  only  two-thirds  that  used  for  the  reversing  layer.  It  seems  probable  that  the  accidental 
errors  of  setting  must  be  several  times  as  great  for  Ha  as  for  the  sharper  and  narrower  lines. 

I  have  already  referred  to  the  marked  widening  and  change  in  appearance  of  Ha  at  the  sun's  limb. 
The  study  of  plates  taken  inside  the  limb  soon  showed  that  the  greater  part  of  this  effect  must  take  place 
within  a  comparatively  narrow  range,  some  3  or  4  mm,  on  a  solar  radius  of  about  84  mm.  This  is  what  we 
should  expect  in  case  the  change  in  the  appearance  of  Ha  is  due  to  the  great  increase  in  the  length  in  path 
of  the  light  at  the  sun's  edge,  since  the  length  of  this  path  decreases  very  rapidly  with  increasing  distance 
inward  from  the  limb.  Accordingly,  two  series  of  observations  have  been  made,  the  first  as  close  to  the 
limb  as  the  slit  could  be  set  without  danger  from  the  introduction  of  chromospheric  light,  and  the  second  at 
an  average  distance  of  about  3  mm  inside  the  limb.  The  details  of  these  observations  and  the  summaries 
of  the  results  are  given  in  Tables  15-18.  The  tables  are  similar  in  arrangement  to  those  containing  the 
data  for  the  reversing  layer.  A  comparison  with  the  values  for  the  normal  places  derived  from  the  two 
series  of  observations  on  the  reversing  layer  is  given  in  Table  35. 


104      AN  INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 
TABLE  15. —  OBSERVATIONS  ON  THE  a  LINE  OF  HYDROGEN  AT  THE  LIMB. 


PLATE 

No. 

GR.  MEAN  DATE. 

0 

A 

1! 

v  +  vl 

8 

PLATE 
No. 

GR.  MEAN  DATE. 

<P 

A 

1! 

»  +  », 

i 

1908          h    m 

0 

km 

km 

0 

1908         h      m 

0 

km 

km 

0 

w  no 

Mar.  24    6  20 

O.2 

o.i  88 

1.98 

2.12 

15.0 

U   I262 

June    9  10  15 

-0.5 

0.196 

2.03 

2.16 

15-3 

I5-I 

0.180 

1.91 

2.05 

15-1 

14-5 

0.182 

1.88 

2.OI 

14.7 

29.9 

0.154 

1.63 

i-75 

14-3 

29-5 

o.i  66 

1.70 

1.82 

14.8 

44-3 

0.127 

1-34 

i-45 

14.4 

44-5 

0.128 

1.32 

i-43 

14.2 

60.4 

0.083 

0.89 

0.96 

13.8 

59-5 

0.087 

0.89 

0-97 

13-6 

6S-3 

0.069 

0.76 

0.82 

13-9 

75-o 

0.046 

0.48 

0-53 

14-5 

75-2 

0.042 

0.50 

o.54 

15.0 

<•>  "5 

May  15     5  10 

-0.4 

0.192 

2.01 

2-15 

iS-3 

W  I27i 

June    9  10  15 

-0-5 

0.195 

2.  02 

2-15 

iS-3 

14.6 

0.184 

1.89 

2.  02 

14.8 

I4-S 

0.184 

1.90 

2.03 

14.9 

29.6 

o-iS3 

i-59 

I.7I 

14.0 

29-5 

0.161 

1.6? 

1-79 

14.6 

44-9 

0.122 

1.28 

i-39 

13-9 

44-S 

0.122 

1.27 

1.38 

13-7 

6o.S 

0.082 

0.86 

0.94 

13-6 

59-5 

0.083 

0.86 

0.94 

13-1 

75-9 

O.O42 

0.44 

0.48 

14.0 

75-o 

0.045 

0.47 

0.52 

14-3 

w  ii8[ 

June    i  10  30 

-0.6 

0.194 

2.02 

2.15 

iS-3 

w  127-2 

June    9  10  15 

-0-5 

0.197 

2.04 

2.17 

iS-4 

14.4 

0.184 

1.92 

2.05 

15.0 

I4-S 

0.182 

1.89 

2.  02 

14.8 

29.4 

0.158 

1.64 

1.76 

14-3 

29-S 

0.164 

1.71 

1.83 

14.9 

44-9 

0.135 

I.4I 

i-Si 

iS-i 

44-S 

0.125 

1.30 

I.4I 

14.0 

60.4 

0.084 

0.88 

o-95 

13-6 

59-5 

0.087 

0.90 

0.98 

13-7 

75-9 

0.042 

0-45 

0-49 

14-3 

75-o 

0.044 

0.46 

0.51 

14.0 

w  ii82 

June    i  10  30 

-0.6 

0.196 

2.04 

2.17 

15-4 

w  129 

June  10     2  40 

-0.5 

0.195 

2.OI 

2.14 

15-2 

14.4 

0.184 

1.92 

2.05 

'S-o 

14-5 

0.185 

1.90 

2.03 

14.9 

29.4 

°-I55 

1.61 

i-73 

14.1 

29-5 

o.i  66 

1.70 

1.82 

14.8 

44-9 

0.128 

i-33 

i-43 

14-3 

44-5 

0.126 

1.30 

I.4I 

14.0 

60.4 

0.086 

0.89 

0.96 

13-8 

S9-5 

0.085 

0.88 

0.96 

13-4 

75-9 

0.046 

0.48 

0.52 

15-2 

74-5 

0.045 

0.46 

0.51 

I3-S 

«J  122 

June    9     2  45 

-o.S 

0.192 

2.00 

2.13 

iS-i 

<*   I3°l 

June  10     2  40 

-0-5 

0.196 

2.02 

2-IS 

iS-3 

14-5 

0.178 

1.86 

1.99 

14.6 

14-5 

0.184 

1.90 

2.03 

14.9 

29-5 

O.I  60 

1.67 

i-79 

14.6 

29-5 

0.162 

1.68 

1.  80 

14.7 

44-5 

O.I  2O 

1.24 

i-35 

13-4 

44-S 

0.125 

1.29 

1.40 

13-9 

59-5 

0.082 

0.85 

0-93 

13-0 

59-S 

0.088 

0.92 

1.  00 

14.0 

7S-° 

0.042 

0.44 

0.49 

13-4 

74-5 

0.046 

0-47 

0.52 

13.8 

<•>  123 

June    9     2  45 

-0.5 

0.196 

2.03 

2.16 

iS-3 

w  I302 

June  10     2  40 

-0.5 

0.196 

2.02 

2.15 

15-3 

14-5 

0.182 

1.89 

2.02 

14.8 

I4-S 

0.184 

1.90 

2.03 

14.9 

29-5 

0.159 

1.65 

i-77 

14.4 

29-S 

0.161 

1.66 

1.78 

I4-S 

44-5 

0.126 

i-3i 

1.42 

14.1 

44-S 

0.125 

1.29 

1.40 

13-9 

59-5 

0.084 

0.88 

0.96 

13-4 

59-5 

0.083 

0.86 

o-94 

13-1 

75-° 

0.041 

0-43 

0.48 

13.2 

74-5 

0.048 

0-49 

o-54 

H-3 

W  124! 

June    9     2  45 

-0.5 

0.192 

1.96 

2.09 

14.8 

w  1311 

June  10     2  40 

-0-5 

0.194 

2.OO 

2.13 

iS-i 

I4-S 

0.185 

1.90 

2.03 

14.9 

I4-S 

0.185 

1.89 

2.  02 

14.8 

29-S 

0.161 

1.65 

1.77 

14.4 

29-5 

0.163 

1.67 

1.79 

14.6 

44-5 

0.126 

1.29 

i-3i 

13-0 

44-5 

0.125 

1.30 

I.4I 

14.0 

59-5 

0.087 

0.91 

o-99 

13-8 

59-5 

0.087 

0.89 

0.97 

13-6 

7S-o 

0.046 

0-47 

0.52 

14-3 

74-5 

0.045 

0.46 

O.SI 

13-5 

<a  i242 

June    9     2  45 

-o.S 

0.196 

2.01 

2.14 

15-2 

<"  1312 

June  10     2  40 

-o-S 

0.193 

1.99 

2.12 

iS-i 

I4-S 

0.187 

I-9I 

2.04 

15.0 

14-5 

0.178 

1.85 

1.98 

14-5 

29-S 

O.I  60 

I.6S 

1.77 

14.4 

29-5 

0.158 

1.62 

1.74 

14.2 

44-5 

0.125 

1.28 

i-39 

13-8 

44-5 

O.I  2O 

1-25 

1-36 

I3-S 

59-5 

0.086 

0.89 

o-97 

13.6 

59-5 

0.080 

0.82 

0.90 

12.6 

75-° 

0.046 

0.47 

0.52 

14-3 

74-S 

0.044 

o-4S 

0.50 

13-3 

<o  125, 

June    g     7  10 

-o-5 

0.196 

2.O2 

2-15 

iS-3 

w  141 

Aug.    543° 

-0-3 

0.193 

2.OI 

2.14 

15-2 

14-5 

0.184 

1.90 

2.03 

14.9 

14-6 

0.183 

I.9I 

2.O4 

iS-o 

29-S 

0.163 

1.69 

1.81 

14.8 

29-S 

o.i  60 

1.67 

1.79 

14.6 

44-5 

0.126 

1.30 

1.41 

14.0 

44-7 

0.124 

I-3I 

I.4I 

14.1 

59-S 

0.084 

0.86 

0.92 

12.9 

59-9 

0.086 

O.gi 

0.98 

13-9 

7S-o 

0.044 

o.4S 

0.50 

13-7 

74-9 

0.046 

0.52 

0.56 

15-3 

U  I2S2 

June    g     7  10 

-0.5 

0.194 

2.01 

2.14 

15-2 

w  144 

Aug.    5     4  30 

-o-3 

0.192 

2.OI 

2.14 

15-2 

I4-S 

0.183 

1.89 

2.02 

14.8 

14.6 

0.183 

I-9I 

2.04 

15.0 

29-S 

0.162 

1.67 

1.79 

14.6 

29-S 

o.i  60 

1.67 

i-79 

14.6 

44-5 

0.128 

i-33 

1-44 

14-3 

44-7 

0.127 

i-34 

1-44 

14.4 

59-S 

0.084 

0.87 

0.96 

13-4 

59-9 

0.088 

0-93 

I.OO 

14-3 

7S-o 

0.042 

°-43 

0.48 

13.2 

74-9 

0.047 

o-S3 

0-57 

iS-S 

W  I26j 

June    9  10  15 

-o-S 

0.195 

2.01 

2.14 

iS-« 

<o  171 

Aug.  27  n  30 

o-3 

0.191 

1.98 

2.12 

iS-i 

14-5 

0.184 

1.90 

2.03 

14.9 

15-2 

0.183 

1.90 

2.03 

14.9 

29-5 

0.163 

1.68 

1.  80 

14.7 

30.0 

0.157 

1.63 

i-75 

14-3 

44-S 

0.126 

1.30 

I-4I 

14.0 

45-o 

0.126 

1.32 

1.42 

14.2 

S9-S 

0.084 

0.86 

0.94 

13-1 

60.2 

0.084 

0.91 

0.98 

14.0 

75-° 

0.044 

o-45 

0.50 

i3-7 

75-o 

0.048 

0-57 

0.60 

16.4 

OBSERVATIONS   ON   THE    a   LINE   OF   HYDROGEN   AT   THE   LIMB. 


TABLE  16.  —  OBSERVATIONS  ON  THE  a  LINE  OF  HYDROGEN  AT  THE  LIMB.     RESULTS  FOR  EACH  LATITUDE. 


0 

V  -\-  V 

E 

0 

.  +  , 

(. 

0 

,  +  ,, 

i. 

0.2 

km 
2.12 

15.0 

IS-I 

km 
2.05 

15.1 

29.9 

km 
•75 

14-3 

0.4 

2.12 

15-3 

14.6 

2.O2 

14.8 

29.6 

14.0 

0.6 

2-15 

'5-3 

14.4 

2.0S 

15.0 

29.4 

'?6 

14-3 

o.6 

2.17 

15-4 

14.4 

2.0S 

15.0 

29.4 

•73 

14.1 

o-S 

2.16 

15-3 

14-5 

2.O2 

14.8 

29-5 

•77 

14.4 

o-5 

2.13 

I4-S 

1-99 

14.6 

29-S 

•79 

14.6 

2.09 

14.8 

I4-S 

2-03 

14.9 

29-5 

•77 

14.4 

0.5 

2.14 

15.2 

14-5 

2.O4 

15.0 

29-5 

•77 

14.4 

0.5 

2.15 

iS-3 

14-5 

2.03 

14.9 

29-5 

.81 

14.8 

2.14 

15-2 

14-5 

2.O2 

14.8 

29-5 

•79 

14.6 

o-S 

2.14 

15.2 

14-5 

2.03 

14.9 

29-S 

.80 

14-7 

o-S 

2.16 

iS-3 

,     J4-5 

2.OI 

14.7 

29-5 

.82 

14.8 

o-S 

2-15 

'5-3 

14-5 

2.03 

14.9 

29-5 

•79 

14.6 

o-S 

2.17 

iS-4 

14-5 

2.02 

14.8 

29-5 

•83 

14.9 

0-5 

2.14 

15-2 

14-5 

2.03 

14.9 

29-S 

.82 

14.8 

o-5 

2.15 

15-3 

14-5 

2.03 

14.9 

29-5 

.80 

14.7 

o-S 

2.15 

15-3 

14-5 

2.03 

14.9 

29-5 

.78 

14-5 

o-5 

2.13 

IS-' 

I4-S 

2.  02 

14.8 

29-S 

•79 

14.6 

o-S 

2.12 

15.1 

14-5 

1.98 

14.5 

29-5 

•74 

14.2 

0-3 

2.14 

15.2 

14.6 

2.04 

15.0 

29-S 

•79 

14.6 

0-3 

2.14 

15-2 

14.6 

2.O4 

15.0 

29-5 

.76 

14.6 

o-3 

2.12 

iS-i 

15.2 

2.03 

14.9 

30.0 

•75 

14-3 

Means,  0.46 

2.145 

15.21 

14.56 

2.027 

14.89 

29-54 

1-783 

14-51 

0 

.  +  ., 

* 

0 

.  +  ., 

£ 

0 

,  +  ., 

i 

44-3 

km 

•45 

14.4 

60.4 

km 
0.96 

13-8 

75-2 

km 
0-54 

15.0 

44-9 

•39 

13-9 

65-3 

0.82 

13-9 

75-9 

0.48 

14.0 

44-9 

•51 

iS-i 

60.5 

0-94 

13.6 

75-9 

0-49 

14-3 

44-9 

•43 

14-3 

60.4 

0-95 

13.6 

75-9 

0.52 

15-2 

44-5 

•42 

14.1 

60.4 

0.96 

13.8 

75-° 

0.48 

13.2 

44-S 

•35 

13-4 

59-5 

0.96 

13-4 

7S-o 

0.49 

13-4 

44-S 

•31 

13.0 

59-5 

0-93 

13-0 

75-o 

0.52 

14-3 

44-5 

•39 

13-8 

59-5 

0.99 

13.8 

75-o 

0.52 

14-3 

44-5 

.41 

14.0 

S9-S 

0.97 

13-6 

7S-o 

0.50 

13-7 

44-S 

•44 

14-3 

59-5 

0.92 

12.9 

75-o 

0.48 

13.2 

44-S 

•41 

14.0 

59-S 

0.96 

i3-4 

7S-o 

0.50 

13-7 

44-S 

•43 

14.1 

59-5 

0-94 

13-' 

7S-o 

0-53 

14-5 

44-S 

•38 

13-7 

59-5 

0.97 

13.6 

7S-o 

0.52 

14-3 

44-S 

•41 

14.0 

59-S 

0.94 

13.1 

75-o 

0.51 

14.0 

44-S 

•41 

14.0 

S9-S 

0.98 

13-7 

74-5 

0-51 

13-5 

44-S 

.40 

13-9 

59-5 

0.96 

i3-4 

74-5 

0.52 

13-8 

44-S 

.40 

13-9 

59-5 

I.OO 

14.0 

74-S 

0-54 

14-3 

44-S 

•41 

14.0 

59-5 

0.94 

13-1 

74-5 

o-S  i 

13-5 

44-5 

-36 

'3-5 

59-S 

o.97 

13-6 

74-S 

0.50 

13-3 

44-7 

.41 

14.1 

59-5 

0.90 

12.6 

74-9 

0.56 

15-3 

44-7 

1-44 

14.4 

59-9 

0.98 

13.9 

74-9 

0-57 

15-5 

4S-o 

1.42 

14.2 

59-9 

I.OO 

14.3 

7S-o 

0.60 

16.4 

60.2 

0.98 

14.0 

Means,  44.59 

1.408 

14.00 

59-89 

0.953 

13.53 

7S-oo 

0.517 

14.20 

106      AN  INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  17.  —  OBSERVATIONS  ON  THE  a  LINE  OF  HYDROGEN  WITHIN  THE  LIMB. 


PLATE 
No. 

GR.  MEAN  DATE. 

0 

A 

11 

f  +  »j 

£ 

PLATE 
No. 

GR.  MEAN  DATK. 

0 

A 

V 

v  +  vl 

J 

1908          h    m 

0 

km 

km 

° 

1808        h     m 

0 

km 

km 

0 

w  116 

May  15     6  30 

O.I 

0.188 

2.03 

2.17 

15.4 

<•>  138 

Aug.    4  12  30 

0.4 

0.182 

1-95 

2.08 

14.8 

14.9 

0.176 

1.90 

2.03 

14.9 

14.3 

0.174 

1.87 

2.00 

14.7 

29.9 

0.151 

1.63 

i-75 

14-3 

30.2 

0.150 

1.61 

1.72 

14.1 

45-i 

O.I  2O 

1.30 

1.41 

14.2 

45-4 

0.116 

1.26 

1.36 

13.8 

60.8 

0.078 

0.84 

0.92 

13-4 

60.6 

0.070 

0.80 

0.8? 

12.6 

76.2 

0.038 

0.42 

0.47 

14.0 

75-7 

0.038      0.41 

0-45 

12.9 

W   I  IQ! 

June     i     o  40 

-0.6 

0.184 

1-99 

2.12 

iS-i 

w  142 

Aug.    5     4  30 

-o-3 

0.187 

2.OO         2.13 

15.1 

14.4 

o.i7S 

1.89 

2.  02 

14.8 

14.6 

0.177 

1.90    |     2.03 

14.9 

29.4 

0.148 

1.  60 

1.72 

14.0 

29-S 

0.151 

1-63       i-75 

14.3 

44-9 

0.119 

1.28 

I.38 

13.8 

44-7 

O.I2I 

1.30 

I.4O 

14.0 

60.4 

0.076 

0.82 

0.89 

12.8 

59-9 

0.080 

0.87 

0-94 

13.3 

75-9 

0.037 

0.40 

0.44 

12.8 

74-9 

0.038 

0.44 

0.48 

13.1 

W   IIQ2 

June     i     o  40 

-0.6 

0.184 

1.99 

2.12 

15-1 

w  143 

Aug.    543° 

-0-3 

0.186 

1.99 

2.12 

15-0 

14-4 

0.172 

1.86 

1.99 

14.6 

14.6 

0.174 

1.86 

1.99 

14.6 

29.4 

0.148 

i.  60 

1.72 

14.0 

29-S 

0.148 

1-59 

1.72 

14.0 

44.9 

0.119 

1.28 

I.38 

13.8 

44-7 

O.IlS 

1.23 

i-33 

13-3 

60.4 

0.074 

0.80 

0.87 

12-5 

59-9 

O.oSo 

0.86 

0-93 

13.2 

75-9 

0.036 

0-39 

0-43 

12.5 

74-9 

0.040 

0.47 

0-51 

13-9 

w  137 

Aug.    4  12  30 

0.4 

0.184 

1.97 

2.IO 

14.9 

(Jl  172 

Aug.  27  ii  30 

0-3 

0.179 

1-93 

2.06 

14.6 

14-3 

0.174 

1.86 

1.99 

14.6 

iS-2 

0-173 

1.85 

1.98 

14.6 

30.2 

0.145 

1.61 

1.72 

14.1 

30.0 

0.146 

i-59 

1.71 

14.0 

45-4 

O.I  2O 

1.29 

i-39 

14.0 

45-° 

0.116 

1.27 

i-37 

13-8 

60.6     0.073 

0.80 

0.87 

12.6 

60.2 

0.077 

0.86 

o-93 

13-3 

75-7 

0.038 

0.41 

0-45 

12.9 

7S-o 

0.040 

0.49 

0.52 

14-3 

TABLE  18.  —  OBSERVATIONS  ON  THE  o  LINE  OF  HYDROGEN  WITHIN  THE  LIMB.     RESULTS  FOR  EACH  LATITUDE. 


0 

,  +  ,, 

« 

0 

»  +  », 

£ 

0 

V  +  tl, 

£ 

° 

km 

° 

» 

km 

• 

° 

km 

» 

O.I 

2.17 

iS-4 

14.9 

2.03 

14.9 

29-9 

i-75 

14-3 

0.6 

2.12 

i5-i 

14.4 

2.O2 

14.8 

29.4 

1.72 

14.0 

0.6 

2.12 

15-1 

14.4 

1.99 

14.6 

29.4 

1.72 

14.0 

0.4 

2.10 

14.9 

14-3 

1.99 

14.6 

30.2 

1.72 

14.1 

0.4 

2.08 

14.8 

14-3 

2.OO 

14-7 

30.2 

1.72 

14.1 

0.3 

2.13 

iS-i 

14.6 

2.03 

14.9 

29-5 

'•75 

14-3 

0-3 

2.12 

iS-o 

14.6 

1.99 

14.6 

29-5 

1.72 

14.0 

°-3 

2  06 

14.6 

15-2 

1.98 

14.6 

30.0 

1.71 

14.0 

Means,   0.4 

2.  112 

15.00 

14.6 

2.OO4 

14.71 

29.8 

1.726 

14.10 

0 

V  +  t] 

£ 

0 

.  +  *, 

£ 

0 

,  +  ,, 

£ 

9 

45-i 

km 

1.41 

14.2 

60.8 

km 
0.92 

13-4 

76.2 

km 

0.47 

14.0 

44-9 

1.38 

13-8 

60.4 

0.89 

12.8 

75-9 

0.44 

12.8 

44-9 

1.38 

13-8 

60.4 

0.87 

12.5 

75-9 

0-43 

12.5 

45-4 

1-39 

14.0 

60.6 

0.87 

12.6 

75-7 

0.45 

12.9 

45-4 

1.36 

13-8 

60.6 

0.87 

12.6 

7S-7 

0-45 

12.9 

44-9 

1.40 

14.0 

S9-9 

0.94 

13-3 

74-9 

0.48 

13-1 

44-7 

i-33 

13-3 

59-9 

0-93 

13.2 

74-9 

0.51 

13-9 

45-o 

i-37 

13-8 

60.2 

0-93 

13-3 

75-o 

0.52 

14-3 

Means,  45.0 

1-378 

13.84 

60.4 

0.902 

12.96 

75-5 

0.469 

13-30 

OBSERVATIONS    ON   CALCIUM. 


107 


10.    SPECIAL  OBSERVATIONS  ON  X  4227  OF  CALCIUM. 

The  line  X  4227  of  calcium  appears  upon  all  of  the  plates  taken  for  the  investigation  of  the  rotation  of 
the  sun  with  the  lines  of  the  reversing  layer.  The  quality  of  these  negatives,  however,  is  not  well  adapted 
for  the  study  of  this  line,  which  is  very  diffuse  and  has  broad  wings  extending  on  either  side.  Accordingly, 
I  have  taken  a  separate  series  of  plates  in  which  the  density  is  made  sufficiently  great  to  reduce  these  wings 
considerably  and  thus  define  the  central  portion  of  the  line  to  somewhat  better  advantage.  In  spite  of 
this  fact  its  measurement  is  difficult,  and  it  is  doubtful  whether  the  degree  of  accuracy  attained  is  any 
higher  than  in  the  case  of  Ha. 

In  Tables  19  and  20  are  found  the  details  of  the  observations  and  a  summary  of  the  results.  The  values 
for  the  normal  places  are  collected  and  compared  with  those  for  the  reversing  layer  in  Table  36. 


TABLE  19.  —  OBSERVATIONS  ON  \  4227  or  CALCIUM. 


PLATE 
No. 

GR.  MEAN  DATE. 

0 

A 

11 

D  +  Uj 

£ 

PLATE 
-No. 

GR.  MEAN  DATE. 

0 

A 

i} 

ZJ  +  tlj 

1 

igo8         h      m 

0 

km 

km 

• 

1908          h     m 

o 

km 

km 

° 

a  149 

Aug.    5  ii  40 

0.4 

0.182 

1-97 

2.10 

14.9 

i»  167 

Aug.  27     7     o 

0.6 

0.184 

2.01 

2.15 

15.3 

IS-S 

0.172 

1.87 

2.OO 

14.7 

15.0 

0.176 

1.92 

2.05 

15.1 

30.2 

0.150 

1.63 

J-75 

14.4 

29.8 

0.152 

1.67 

1.79 

14.6 

45-6 

O.I  1  1 

1.  21 

i-3i 

13-3 

44-8 

0.119 

1.30 

1.40 

14.0 

60.8 

0.070 

0.77 

0.84 

12.2 

60.0 

0.074 

0.85 

0.92 

13.1 

75-5 

0.036 

0.44 

0.48 

13.6 

74.8 

0.038 

0.42 

0.46 

12.5 

u  150 

Aug.    s  ii  40 

0.4 

0.180 

i-95 

2.08 

14.8 

u  168 

Aug.  27     7     o 

0.6 

0.182 

1.98 

2.12 

15.0 

15-3 

0.172 

1.86 

1.99 

14.6 

15.0 

0.176 

1.91 

2.04 

15.0 

30.2 

0.147 

i.  60 

1.72 

I4.I 

29.8 

0.150 

1.64 

I.76 

14.4 

45-6 

O.I  1  1 

1.  21 

i-3i 

13-3 

44.8 

0.119 

1.30 

1.40 

14.0 

60.8 

0.068 

0-75 

0.82 

II.9 

60.0 

0.077 

0.85 

0.92 

13.1 

75-5 

0-035 

O.42 

0.46 

13-0 

74-8 

0.044 

0-54 

0.58 

15.7 

01  152 

Aug.    6     5  40 

0-3 

0.185 

2.01 

2.14 

15.2 

u  169 

Aug.  27     70 

0.6 

0.184 

2.01 

2-15 

15.3 

iS-2 

0.171 

1.85 

1.98 

14.6 

15-0 

0.176 

1.92 

2.03 

14.9 

3o.i 

0.148 

1.62 

1-74 

14-3 

29.8 

0.152 

1.62 

1.74 

14.2 

45-2 

O.II2 

1.22 

1.32 

'3-3 

44-8 

0.118 

1.29 

i-39 

13.9 

60.4 

O.O72 

0.79 

0.86 

12.4 

60.0 

0.074 

0.82 

0.89 

12.6 

75-4 

0.034 

0.41 

0-45 

12.7 

74-8 

0.043 

o-S3 

o.S7 

15.4 

w  153     ,  Aug.    6     5  40 

°-3 

0.183 

i-99  , 

2.12 

IS-I 

w  170 

Aug.  27     70 

0.6 

o.i  86 

2.  02 

2.16 

15.3 

15.2 

O.I7I 

1.86 

1.99 

14.6 

15-0 

0.176 

1.92 

2.05 

15.1 

30.1 

0.148 

1.64 

1.76 

144 

29.8 

0.149 

1.63 

1-75 

14-3 

45-2 

O.II2 

1.22 

1.32 

13-3 

44-8 

0.120 

1.32 

1.42 

14.2 

60.4 

0.070 

0.77 

0.84 

12.  1 

60.0 

O.o8o 

0.89 

0.96 

13.6 

75-4 

0.033 

o-39 

0-43 

12.  1 

74.8 

O.O42 

0.51 

0-55 

14.9 

w  154       Aug.    6     5  40 

°-3 

O.lSo 

1.97 

2.10 

14.9 

«  188 

Oct.     22    10    30 

—  O.I 

0.184 

1.99 

2-13 

15.1 

15-2 

0.174 

1.89 

2.O2 

14.9 

14.8 

O.I72 

1.86 

2.00 

14.7 

30.1 

0.148 

1.64 

1.76 

14.4 

29.8 

0.153 

1.66 

1.79 

14.6 

45-2 

O.II4 

1.23 

i-33 

13-4 

44.9 

O.II5 

1-25 

1.36 

13.6 

60.4 

0.067 

0.74 

0.81 

II.6 

60.2 

0.075 

0.79 

0.87 

12.4 

75-4 

0.032 

0.38 

0.42 

n.8 

75-9 

0.039 

0-45 

0-49 

14.3 

—O.I 

O.lSl 

1.96 

2.IO 

14.9 

<"  iS7 

Aug.  13     s  10 

-o-3 

0.184 

1.99 

2-13 

15-1 

w  189 

Oct.    22    IO    30 

14.8 

0.175 

1.88 

2.02 

14.8 

14.6 

0.176 

1.91 

2.04 

15.0 

29.8 

0.154 

1.67 

1.  80 

14.7 

2Q-S 

0.147 

i-59 

1.71 

13-9 

44-9 

0.118 

1.28 

1-39 

13.9 

44.1 

0.116 

1.26 

1.36 

13-4 

60.2 

0.079 

0.85 

0-93 

13-3 

S8-4 

0.073 

0.81 

0.89 

I2.O 

75-9 

0.037 

0.44 

0.48 

14.0 

72.0 

0.037 

0.42 

0.47 

10.8 

w  158 

Aug.  13     5  10 

-o-3 

0.182 

1.97 

2.  II 

15.0 

14.6 

0.176 

1.91 

2.04 

15-0 

29-5 

0.146 

1.58 

1.70 

13-9 

44.1 

0.114 

1-23 

i-33 

13-1 

58-4 

0.074 

0.8  1 

0.89 

I2.O 

72.0 

0.041 

0.48 

o-53 

12.2 

I08      AN   INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


TABLE  20.  —  OBSERVATIONS  ON  x  4227  OF  CALCIUM.    RESULTS  FOR  EACH  LATITUDE. 


0 

JJ  +  Uj 

£ 

0 

tl  +  Bj 

{ 

0 

»  +  », 

£ 

• 

km 

. 

« 

km 

0 

0 

kra 

„ 

0.4 

2.10 

14-9 

15-3 

2.OO 

14.7 

30.2 

•75 

14.4 

0.4 

2.08 

14.8 

15-3 

1.  99 

14.6 

30.2 

.72 

14.1 

0-3 

2.14 

15-2 

15-2 

1.98 

14.6 

30.1 

•74 

14-3 

°-3 

2.12 

15-1 

15-2 

1-99 

14.6 

30.1 

.76 

14.4 

°-3 

2.10 

14-9 

15-2 

2.  02 

14.9 

30.1 

.76 

14.4 

°-3 

2-13 

15-1 

14.6 

2.O4 

15.0 

29-5 

•71 

13-9 

°-3 

2.  II 

15-0 

14.6 

2.04 

15.0 

29-5 

.70 

13-9 

o.ft 

2-IS 

iS-3 

15.0 

2.0S 

15-1 

29.8 

•79 

14.6 

0.6 

2.12 

15.0 

15.0 

2.04 

15.0 

29.8 

.76 

14.4 

0.6 

2-15 

iS-3 

15-0 

2-03 

14.9 

29.8 

•74 

14.2 

0.6 

2.16 

iS-3 

15.0 

2.05 

15-1 

29.8 

•75 

14-3 

O.I 

2.13 

iS-i 

14.8 

2.OO 

H-7 

29.8 

•79 

14.6 

O.I 

2.IO 

14.9 

14.8 

2.02 

14.8 

29.8 

.80 

14.7 

Means,  0.38 

2.122 

15-07 

15.00 

2.OIQ 

14-85 

29.88 

1-752 

14.32 

0 

»  +  », 

J 

<t> 

»  +  r, 

£ 

0 

»  +  fj 

J 

. 

km 

• 

0 

km 

0 

0 

km 

„ 

45-6 

I-3I 

13-3 

60.8 

0.84 

12.2 

75-5 

0.48 

!3.6 

45-6 

l-3> 

13-3 

60.8 

0.82 

II.9 

75-5 

0.46 

13.0 

45-2 

1.32 

13-3 

60.4 

0.86 

12.4 

75-4 

o-4S 

12.7 

45-2 

•32 

13-3 

60.4 

0.84 

12.  1 

75-4 

o.43 

12.  1 

45-2 

•33 

13-4 

60.4 

0.81 

n.6 

75-4 

0.42 

n.8 

44.1 

•36 

13-4 

58.4 

0.89 

12.0 

72.0 

0.47 

10.8 

44.1 

•33 

13-1 

58-4 

0.89 

12.0 

72.0 

o-53 

12.2 

44.8 

.40 

14.0 

60.0 

0.92 

I3-I 

74.8 

0.46 

12-5 

44.8 

.40 

14.0 

60.0 

0.92 

I3-I 

74-8 

0.58 

15-7 

44.8 

•39 

13-9 

60.0 

0.89 

12.6 

74-8 

o-57 

iS-4 

44.8 

•42 

14.2 

60.0 

0.96 

13.6 

74-8 

0-55 

14.9 

44-9 

•36 

13-6 

60.2 

0.87 

12.4 

75-9 

o-49 

14-3 

44-9 

•39 

13-9 

60.2 

0-93 

13-3 

75-9 

0.48 

14.0 

Means,  44.92 

1-357 

13-52 

60.00 

0.880 

12.48 

74.78 

0.490 

I3-3I 

DISCUSSION  OF  THE  RESULTS. 


ii.    SYSTEMATIC  DEVIATIONS  OF  VELOCITY  or  ROTATION  DERIVED  FROM  VARIOUS  LINES 

OF  THE  REVERSING  LAYER. 

ONE  of  the  most  important  questions  connected  with  the  results  of  this  investigation  is  whether  the 
lines  of  different  elements  give  values  which  differ  from  one  another  in  any  systematic  way,  indicating  a 
longer  or  shorter  period  of  rotation  for  the  various  elements  in  the  sun's  atmosphere.  The  behavior  of 
the  individual  lines  in  this  regard  will  be  shown  best  if  we  form  the  difference  in  the  value  of  the  angular 
velocity  of  £  for  each  line  from  that  of  the  mean  of  all  the  lines.  Any  systematic  effect  will  show  itself 
at  once  by  the  marked  preponderance  of  the  positive  or  the  negative  sign  in  the  residuals.  The  results  of 
such  a  comparison  are  given  for  the  two  series  of  observations  in  Tables  21  and  22.  In  forming  these  differ- 
ences I  have  rounded  off  the  results  to  one  place  of  decimals,  although  the  reduction  tables  have  been 
carried  to  two  places.  This  has  seemed  desirable  in  order  to  facilitate  rapid  comparison  of  the  results. 
In  the  formation  of  the  mean  deviations  for  several  latitudes,  however,  the  second  place  has  been  retained. 

An  examination  of  these  tables  leads  to  several  important  conclusions.  The  most  striking  of  these  are, 
on  the  one  hand,  the  systematically  low  values  given  by  the  lanthanum  line  at  X  4196.699,  the  cyanogen 
lines  A.  4197.257  and  X  4216.136,  and  the  enhanced  line  of  titanium  at  X  4290.377  ;  and,  on  the  other  hand, 
the  high  values  given  by  X  4257.815  and  possibly  one  or  two  other  lines  in  the  list.  The  evidence  for  con- 
cluding that  lanthanum  and  cyanogen  occupy  a  relatively  low  level  in  the  sun's  atmosphere  has  already 
been  referred  to  in  connection  with  the  discussion  of  the  selection  of  the  lines  chosen  for  measurement. 
In  the  case  of  lanthanum  reference  should  be  made  to  an  additional  point  of  evidence,  namely,  that  its 
lines,  like  those  of  other  elements  of  very  high  atonu'c  weight,  are  much  weakened  at  the  sun's  limb.  The 
fact,  accordingly,  that  the  lines  of  cyanogen  and  lanthanum  give  consistently  low  values  for  the  angular 
velocity  of  rotation  indicates  that  the  sun's  period  of  rotation  increases  as  we  approach  its  surface,  or  that 
the  outer  layers  of  the  solar  atmosphere  move  more  rapidly  than  those  lying  close  to  the  photosphere. 
This  is  in  agreement  with  the  results  found  for  hydrogen  and  other  substances  which  rise  to  a  great  height 
above  the  solar  surface,  and  to  which  extended  reference  will  be  made  later. 

TABLE  21. — DEVIATIONS  OF  ANGULAR  VELOCITY  FOR  INDIVIDUAL  LINES  FROM  MEAN  VALUE.    OBSERVATIONS  OF  1906-1907. 


\ 

ELEMENT. 

O°2 

?!? 

I5?o 

22?7 

29!  8 

37?8 

44?6 

S2?7 

S9°6 

6s?6 

75?i 

8o?4 

4196.699 

La 

O.O 

O.O 

—  O.I 

—  o. 

—  O.I 

—0.2 

—  0.2 

-0-3 

-0.4 

0 

-0-3 

-0.8 

-o-3 

4197-257 

CN 

0.0 

0.0 

O.O 

—  0. 

O.O 

—  O.2 

—  O.I 

-0-3 

—0.2 

-o-3 

-0.8 

-0.4 

4203.730 

Cr 

+  0.2 

+0.1 

+0.1 

0.0 

+0.1 

O.O 

0.0 

0.0 

+0.1 

O.O 

+0.2 

+0.2 

4209.144 

Zr 

+0.2 

+0.1 

+0.1 

+0. 

+0.2 

+0.1 

+0.2 

O.O 

+0.2 

+0.1 

+0.1 

+0.1 

4216.136 

CN 

—  O.I 

0.0 

—  O.I 

—  0. 

—  O.2 

—  O.I 

—  O.2 

-0.3 

—  0.2 

-0-4 

-0.8 

-o-3 

4220.509 

Fe 

+0.1 

+0.1 

+0.1 

+0. 

+0.2 

+0.1 

+0.1 

0.0 

O.O 

0.0 

+0.2 

+0.4 

4232.887 

Fe 

+0.1 

+0.1 

+0.1 

+0. 

+0.1 

0.0 

0.0 

O.O 

+0.1 

+0.1 

+0.1 

+0.1 

4257-813 

Mn 

+0.1 

+0.2 

+0.1 

+0.2 

+0.2 

+0.2 

+0.2 

+0.2 

+0.2 

+0.3 

+0.6 

+0.3 

4258.477 

Fe 

0.0 

O.O 

O.O 

0.0 

O.O 

0.0 

0.0 

0.0 

+0.2 

+0.1 

+0.2 

-0.4 

4265.418 

Fe 

0.0 

O.O 

+0.1 

O.O 

0.0 

0.0 

0.0 

O.O 

+0.1 

0.0 

0.0 

O.O 

4266.081 

Mn 

O.O 

+  0.1 

0.0 

+0.1 

+0.1 

+0.1 

+0.1 

+0.2 

+0.2 

+0.2 

+0.5 

+0.4 

4268.915 

Fe 

0.0 

O.O 

O.O 

0.0 

O.O 

O.O 

0.0 

0.0 

O.O 

+0.2 

+0.1 

0.0 

4276.826 

-Zr 

0.0 

+0.1 

0.0 

O.O 

0.0 

0.0 

0.0 

0.0 

0.0 

+0.1 

0.0 

O.O 

4284.838 

Ni 

O.O 

—  O.I 

O.O 

O.O 

—  o. 

O.O 

O.O 

+0.1 

0.0 

0.0 

O.O 

0.0 

4287.566 

Ti 

0.0 

—  O.I 

O.O 

0.0 

—  o. 

O.O 

0.0 

0.0 

+0.1 

+0.1 

+0.1 

+0.1 

4288.310 

Ti,  Fe 

0.0 

—O.I 

—  O.I 

O.O 

O.O 

0.0 

—  O.I 

+0.1 

0.0 

0.0 

+0.1 

O.O 

4290.377 

Ti 

-0.2 

—  0.2 

—  O.I 

—  O.I 

—  0. 

—  O.I 

—O.I 

+0.1 

—O.I 

O.O 

—  O.I 

-0.4 

4290.542 

Fe 

—  O.I 

—  O.I 

—O.I 

0.0 

—  o. 

0.0 

—  O.I 

0.0 

—O.I 

0.0 

+0.1 

—  O.I 

4291.630 

Fe 

—  O.I 

—O.I 

—  O.I 

—O.I 

—  0. 

0.0 

O.O 

0.0 

—O.I 

+0.1 

+0.4 

O.O 

4294.936 

Zr 

—O.I 

—  O.I 

—  O.I 

—O.I 

—  0. 

O.O 

O.O 

+0.1 

+0.1 

0.0 

O.O 

0.0 

109 


110      AN   INVESTIGATION   OF  THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 
TABLE  22. —  DEVIATIONS  OF  ANGULAR  VELOCITY  FOR  INDIVIDUAL  LINES  FROM  MEAN  VALUE.    OBSERVATIONS  OF  1908. 


X 

ELEMENT. 

o?4 

4!  I 

ll°2 

I4?9 

JQ°2 

2g°8 

34?  I 

44?» 

49?6 

60!  I 

65?° 

7S?o 

79?  I 

4196.699 

La 

—  0.2 

—  O.I 

—  O.I 

—  O.I 

—  O.I 

0 

—  O.I 

o 
—  O.I 

—  O.I 

o 
—  O.I 

—  O.2 

—  O.2 

-0.4 

—  0.2 

4197-257 

CN 

—  O.I 

—  O.I 

—  O.I 

-O.I 

—  O.I 

—  O.I 

—  O.I 

—  O.I 

-O.I 

—  0.2 

—  0.2 

-0.3 

—  O.I 

4203.730 

Cr 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

0.0 

0.0 

—  O.I 

—  O.I 

4207.566 

CN 

o.o 

o.o 

0.0 

o.o 

+  0.1 

o.o 

o.o 

o.o 

o.o 

o.o 

—  O.I 

-0.5 

—  O.I 

4216.136 

CN 

—  O.I 

—  O.I 

—  O.I 

—  O.I 

o.o 

-0.2 

—  O.I 

—  0.2 

—  O.I 

—  O.I 

—  O.2 

-0.3 

-0.4 

4220.509 

Fe 

0.0 

0.0 

o.o 

0.0 

0.0 

0.0 

+0.1 

0.0 

+0.! 

o.o 

0.0 

+0.1 

—  0.2 

4232.887 

Fe 

o.o 

o.o 

o.o 

o.o 

+0.1 

o.o 

o.o 

—  O.I 

0.0 

—  O.I 

0.0 

o.o 

-0.3 

4233-328 

Mn 

o.o 

+0.1 

o.o 

o.o 

+0.1 

o.o 

o.o 

o.o 

0.0 

0.0 

o.o 

-o-3 

-0.2 

4257.815 

Mn 

+0.1 

0.0 

0.0 

+  0.1 

+0.1 

+0.1 

+  0.1 

+0.1 

+0.1 

+  0.1 

+  0.1 

+0.3 

+0.3 

4258.477 

Fe 

0.0 

0.0 

o.o 

+0.1 

0.0 

+  0.1 

0.0 

+  0.1 

0.0 

o.o 

o.c 

+0.1 

+0.2 

4265.418 

Fe 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

0.0 

0.0 

0.0 

0.0 

+  0.2 

4266.081 

Mn 

+0.1 

+0.1 

0.0 

o.o 

o.o 

+0.1 

o.o 

+0.1 

o.o 

o.o 

+  0.1 

+  0.2 

+0.3 

4268.915 

Fe 

+  0.1 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

+  0.! 

+0.2 

+0.2 

+0.2 

4276.836 

-Zr 

o.o 

0.0 

o.o 

o.o 

o.o 

0.0 

0.0 

0.0 

0.0 

+0.1 

0.0 

+  0.2 

+  0.1 

4283.169 

Co. 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

+0.1 

o.o 

o.o 

o.o 

4283.838 

Ni 

o.o 

0.0 

0.0 

—  O.I 

—  O.I 

—  O.I 

o.o 

—  O.I 

o.o 

o.o 

o.o 

+0.2 

—  O.I 

4287.566 

Ti 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

—  O.I 

o.o 

+0.1 

0.0 

4288.310 

Ti,  Fe 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

0.0 

+  0.1 

o.o 

+  0.1 

+0.3 

4289.525 

Ca 

o.o 

o.o 

o.o 

o.o 

o.o 

+0.1 

o.o 

+0.1 

+  0.1 

o.o 

+  0.1 

+  0.1 

+  0.2 

4290.377 

Ti 

0.0 

0.0 

0.0 

0.0 

—  O.I 

0.0 

0.0 

—  O.I 

0.0 

—  O.I 

0.0 

—  O.I 

—  O.I 

4290.542 

Fe 

0.0 

0.0 

0.0 

+0.1 

0.0 

+0.1 

+0.1 

+0.1 

0.0 

+  0.1 

+0.1 

+0.2 

—  O.I 

4291.630 

Fe 

+0.1 

o.o 

o.o 

o.o 

o.o 

+0.1 

o.o 

+0.1 

+0.1 

+0.1 

+0.1 

+0.1 

+  0.2 

The  agreement  of  the  two  series  of  observations  as  regards  the  amount  of  this  effect  in  the  lower  lati- 
tudes is  excellent.  The  1906-1907  observations  give  — o.io  for  the  lanthanum  line  between  o°  and  45°  of 
Latitude,  and  the  1908  observations  give  —  o°n.  Similarly  for  the  mean  of  the  cyanogen  lines  the  earlier 
observations  give  —0.09  and  the  later  observations  —  o.u.  A  difference  of  —  o.io  in  the  value  of  the 
angular  velocity  at  the  equator  would  correspond  to  a  difference  in  the  rotation  period  of  about  0.17  day. 

The  enhanced  line  of  titanium  at  X  4290.377  is  of  especial  interest.  It  is  well  known  from  observations 
of  the  spectrum  of  the  chromosphere  that  the  enhanced  lines,  as  a  class,  are  relatively  much  more  promi- 
nent in  the  chromosphere  than  they  are  in  the  ordinary  solar  spectrum.  This  would  apparently  indicate  a 
higher  average  level  in  the  sun's  atmosphere.  On  the  other  hand,  the  line  is  considerably  shifted  at  the 
limb  of  the  sun,*  and  this  points  to  a  relatively  low  level.  The  systematically  low  value  of  the  angular 
velocity  of  rotation  furnishes  additional  evidence  in  the  same  direction.  Further  evidence  is  afforded  on 
this  subject  by  the  only  other  enhanced  line  in  either  list,  that  due  to  iron,  X  4233.328.  The  mean  value 
of  I  in  its  case  agrees  closely  with  the  mean  derived  from  all  the  lines.  Since  it  is  a  very  prominent  chromo- 
spheric  line,  however,  the  fact  that  it  does  not  give  a  large  value  for  the  angular  rate  of  rotation  is  strong 
evidence  that  it  does  not  originate  at  any  very  considerable  height  in  the  sun's  atmosphere.  The  explana- 
tion of  this  apparent  discrepancy  of  results  is  not  at  present  clear.  It  seems  fairly  probable  that  the  diffi- 
culty will  be  found  to  be  due  to  the  interpretation  of  the  chromospheric  results,  and  that  the  relative 
strength  of  the  enhanced  lines  does  not  necessarily  indicate  a  higher  level  in  the  solar  atmosphere.  One 
hypothesis  founded  on  this  basis  was  published  by  Evershed  in  1900  (18).  Another  possible  explanation  is 
indicated  by  some  preliminary  results  obtained  by  Mr.  Gale  and  myself  while  working  on  the  displacements 
in  the  spectrum  of  a  spark  under  pressure,  but  considerable  additional  material  will  be  necessary  to  give  it 
adequate  weight. 

Of  the  lines  which  give  positive  residuals,  that  due  to  manganese  at  X  4257.815  is  the  most  prominent 
in  both  series  of  observations.  This  line  is  not  a  chromospheric  line,  at  least  of  any  considerable  intensity, 
nor  is  it  much  affected  at  the  sun's  limb.  In  sun-spots  it  is  slightly  strengthened.  There  is  some  evidence 
in  both  sets  of  observations,  especially  in  the  earlier,  that  X  4266.081  gives  similar  results.  It  is  included 

*  In  referring  to  shifts  at  the  sun's  limb,  the  differential  shift  compared  with  the  center  of  the  sun  as  freed  from  rotational  displace- 
ments is  always  understood.  For  convenience  we  may  designate  it  as  "pressure"  shift,  although  pressure  alone  is  probably  not  suffi- 
cient to  account  for  all  the  effects  observed. 


DEVIATIONS   IN   HIGHER   LATITUDES. 


Ill 


as  a  chromospheric  line  in  some  lists,  but  is  of  comparatively  slight  intensity.  The  three  lines  in  the  list 
which  are  most  strengthened  at  the  sun's  limb,  X  4232.887,  X  4258.477,  and  A.  4291.630,  all  give  values  close 
to  the  mean,  with  a  very  slight  tendency  toward  positive  residuals.  Reference  should  also  be  made  to  the 
line  at  X  4207.566.  This  is  assigned  in  Rowland's  table  to  iron,  but  in  the  list  of  corrections  is  transferred 
to  carbon.  Its  appearance  is  strongly  indicative  of  a  compound  origin,  as  it  is  much  wider  than  other  lines 
of  the  same  intensity  in  its  vicinity.  At  the  limb  of  the  sun  it  shows  a  considerable  displacement  —  so 
much  larger,  in  fact,  than  other  neighboring  cyanogen  lines  as  to  make  its  composite  character  almost 
certain.  Accordingly,  the  evidence  afforded  by  this  line  can  not  be  considered  as  contradictory  to  that  of 
the  other  cyanogen  lines  in  the  list. 

12.    INCREASE  OF  DEVIATIONS  IN  HIGHER  LATITUDES. 

Another  possible  conclusion  of  great  importance  is  afforded  by  an  inspection  of  these  tables,  but  it 
should  be  accepted  with  considerable  caution.  This  is  the  apparent  increase  in  the  amount  of  the  devia- 
tions for  such  lines  as  show  systematically  large  or  small  values  of  the  angular  velocity  toward  the  sun's 
pole.  Thus  the  average  deviation  from  the  mean  for  the  two  cyanogen  lines  X  4197.257  and  X  4216.136 
between  latitudes  60°  and  80°  is  —  o°3  as  against  — o?i  between  latitudes  o°  and  20°.  Similarly  the  lan- 
thanum line  X  4196.699  gives  — o?3  against  — o?i,  while  the  manganese  line  X  4257.815  gives  +o?3  against 
+o?i.  The  1908  observations  give  considerably  smaller  values  for  these  differences  than  do  the  earlier 
results,  but  the  effect  is  still  well  marked,  the  values  in  the  higher  latitudes  amounting  to  more  than  twice 
those  near  the  equator.  It  is  of  course  true  that  a  very  small  difference  in  linear  velocity  in  the  higher 
latitudes  corresponds  to  a  large  difference  in  angular  velocity,  and  so  a  wider  range  is  to  be  expected 
among  the  values  for  the  individual  lines.  For  example,  at  the  equator  a  change  in  the  linear  velocity  of 
o.oi  km  corresponds  to  0.07  in  the  angular  velocity,  while  at  80°  of  latitude  it  corresponds  to  0.41.  If  due 
to  this  cause,  however,  we  should  expect  the  values  of  the  differences  in  the  higher  latitudes  to  be  both  larger 
and  smaller  than  those  near  the  equator  and  not  to  exhibit  this  systematic  increase.  In  spite  of  this  effect, 
the  evidence  might  be  considered  rather  doubtful  if  it  were  not  for  the  strong  support  afforded  by  the 
behavior  of  two  lines  of  elements  which  rise  to  a  great  height  in  the  sun's  atmosphere.  These  are  the  a  line 
of  hydrogen  and  X  4227  of  calcium.  The  results  for  these  lines  will  be  considered  in  detail  at  a  later  point 
in  this  discussion,  though  the  evidence  furnished  by  them  regarding  changes  of  rotation  rate  in  the  higher 
latitudes  properly  belongs  here.  In  the  brief  accompanying  table  are  given  the  differences  for  such  lines 
as  show  systematically  large  or  small  values  of  the  angular  velocity  from  a  mean  obtained  from  all  the  lines 
in  the  reversing-layer  list. 


X 

ELEMENT. 

LATITUDE 

0°  -  20° 

LATITUDE 
60°  -  80° 

4196.699 

La 

—  O.I 

-0.3 

4197-257  \ 
4216.136] 

CN 

—  O.I 

-o-3 

4257-815 

Mn 

+  0.1 

+  0.3 

4226.904 

Ca 

+  0.4 

+  1.6 

6563.045 

II 

+  0.6 

+  2.8 

The  great  increase  in  the  value  of  £  in  the  case  of  the  last  two  lines  is  most  striking,  and  in  spite  of  the 
relatively  low  degree  of  accuracy  attained  in  the  measurement  of  these  lines  as  compared  with  those  of  the 
reversing  layer,  such  differences  as  these  must  certainly  be  considered  as  real.  Accordingly,  we  may  say 
that  there  is  a  strong  presumption  for  concluding  that,  in  the  case  of  lines  showing  relatively  large  or  small 
velocities  at  the  equator,  the  values  of  deviations  from  the  mean  increase  in  the  higher  latitudes.  It  is  of 
interest  to  note  that  the  variations  in  angular  velocity  which  Halm  believed  he  had  discovered  during  the 
different  years  included  in  his  observations  were  greatest  toward  the  pole. 


112      AN  INVESTIGATION   OF   THE   ROTATION  PERIOD   OF  THE   SUN  BY  SPECTROSCOPIC   METHODS. 


13.    MEAN  RESULTS  FOR  THE  REVERSING  LAYER  —  VARIABILITY  OF  THE  SOLAR  ROTATION  - 
COMPARISON  OF  RESULTS  WITH  THOSE  OF  OTHER  OBSERVERS. 

We  may  now  pass  on  to  an  investigation  of  the  general  results.  While  it  appears  clear  from  the  pre- 
ceding considerations  that  certain  lines  in  the  list  give  values  which  are  systematically  high  or  low,  the 
number  of  lines  of  the  two  kinds  seems  to  be  so  nearly  equal  that  no  appreciable  error  from  this  source  will 
affect  the  mean  taken  from  all  the  lines.  If  we  form  means  of  the  results  of  the  two  series  of  observations 
for  the  normal  points  of  latitude  indicated  in  Tables  6  and  13,  we  obtain  the  values  given  in  Table  23. 
The  weights  are  according  to  the  number  of  observations.  The  results  are  shown  graphically  in  Fig.  i , 
the  dotted  curve  corresponding  to  the  1906-1907  observations  and  the  full-line  curve  to  the  1908  observa- 
tions. In  each  case  the  agreement  of  the  points  with  the  curve  is  excellent,  the  largest  deviation  falling 
at  the  points  of  lowest  weight. 


Km 

"^ 

-V 

V-N 

, 

\ 

\ 

s 

x^ 

^V      X 
>»      V 

^V      N 

V 

N,          N 

X 

•v      X 

% 

°x 

v+v. 

\ 

0"                <f>                  I 

0'                                       2 

0* 

O'                                   4 

0* 

if                            6 

n6                          t 

D'                                8 

3-                           act 

FIG.  i. —  Curves  representing  the  variation  of  radial  velocity  with  heliographic  latitude  for  the  two  series  of  observations  1906-1907 
and  1908.     The  broken-line  curve  represents  the  1906-1907  observations,  the  full-line  curve  those  of  1908. 


RESULTS  FOR  THE  REVERSING  LAYER. 

TABLE  23.  —  MEAN  RESULTS  FOR  THE  REVERSING  LAYER. 


OBSERVATIONS  OF  1906-1907. 

OBSERVATIONS  OF  1908. 

0 

WEIGHT. 

tl  +  Hj 

« 

PERIOD. 

0 

WEIGHT. 

»  +  », 

1 

PERIOD. 

0 

km 

0 

days 

0 

km 

0 

days 

O.2 

21 

2.074 

14-73 

24-44 

0.4 

21 

2.062 

14.64 

24.59 

7-7 

IS 

2.028 

14.53 

24.77 

4.1 

IS 

2.040 

14-53 

24.78 

iS-O 

24 

1-957 

14.40 

25.00 

II.  2 

12 

.991 

14.40 

25.00 

22.7 

1.3 

1.811 

13-94 

25.82 

14.9 

18 

•944 

14.28 

25.21 

29.8 

24 

1.676 

13-71 

26.26 

19.2 

14 

.867 

14.04 

25.64 

37-8 

16 

1.461 

13-13 

27-42 

29.8 

16 

.669 

13.65 

26.37 

44.6 

23 

1.283 

1  2.80 

28.12 

34-i 

IS 

•557 

J3-35 

26.96 

52-7 

18 

i.  060 

12-43 

28.96 

44-8 

17 

.287 

12.87 

27.97 

59-6 

24 

0.867 

12.15 

29.63 

49.6 

16 

•137 

12.45 

28.92 

65.6 

20 

0.604 

11.96 

30.10 

60.  i 

22 

0.806 

11.49 

31-33 

75-i 

33 

0-435 

11.98 

30-OS 

65.0 

17 

0.671 

11.30 

31-86 

80.4 

ii 

0.277 

11.80 

30.51 

75-o 

17 

0.396 

10.86 

33-15 

79.1 

7 

0.272 

10.25 

35-12 

The  most  interesting  question  involved  in  these  results  is  whether  an  actual  variation  in  the  sun's  rate 
of  rotation  is  indicated.  To  facilitate  direct  comparison  the  values  from  the  two  series  of  observations  for 
every  5°  of  latitude  are  given  in  Table  24.  They  are  obtained  from  empirical  formulas  which  satisfy  the 
observations  closely.  The  derivation  of  these  formulae  will  be  indicated  later  in  the  discussion. 

TABLE  24.  —  COMPARISON  OF  THE  RESULTS  FOR  THE  Two  SERIES. 


v  +  vl 

1 

1906-1907 

1908 

DIFFERENCE. 

1906-1907 

1908 

DIFFERENCE. 

0 

km 
2.064 

km 
2-053 

km 
+  O.OII 

14.63 

0 

14.61 

+  O.O2 

5 

2.052 

2.041 

+  0.01  1 

14.60 

14-58 

+  0.02 

10 

2.015 

2.OO6 

+  0.009 

14.51 

14.49 

+  0.02 

15 

1.956 

1.947 

+  0.009 

14.37 

14.34 

+  0.03 

20 

1.877 

.869 

+  0.008 

14.18 

14.14 

+  0.04 

25 

1.779 

.772 

+  0.007 

13-94 

13.89 

+  0.05 

30 

1.666 

.660 

+  0.006 

13.68 

13.60 

+  0.08 

35 

1-542 

•534 

+  0.008 

13-39 

13.28 

+  O.II 

40 

1.409 

•399 

+  O.OIO 

13.10 

12.94 

+  0.16 

45 

1.272 

•  258 

+  0.014 

12.81 

I2-59 

+  0.22 

So 

1.132 

.114 

+  0.018 

12.54 

12.24 

+  0.30 

55 

0.992 

0.968 

+  0.024 

12.30 

11.90 

+  0.40 

60 

0.852 

0.822 

+  0.030 

12.  II 

11.58 

+  0-53 

65 

0-713 

0.678 

+  0.035 

11.97 

11.29 

+  0.68 

70 

0.576 

0-537 

+  0.039 

II.9O 

11.04 

+  0.86 

75 

0-437 

0.400 

+  0.037 

11.91 

10.84 

+  1.07 

An  inspection  of  these  results  shows  that  the  1908  observations  give  slightly  smaller  values  than  the 
earlier  series  between  latitudes  o°  and  40°,  and  decidedly  smaller  values  between  45°  and  80°.  In  the  lower 
latitudes  the  largest  difference  is  at  the  equator  and  amounts  to  o.oi  i  km  for  v  +  vv  Although  this  is  per- 
haps larger  than  might  be  expected  from  the  internal  agreement  of  the  measures,  it  is  hardly  sufficient 
to  warrant  the  conclusion  that  a  source  of  systematic  error  is  present,  or  that  any  variation  in  the  sun's 
rate  of  rotation  is  indicated. 

In  the  higher  latitudes  the  case  is  somewhat  different,  however.  At  latitude  70°  a  maximum  difference 
of  0.039  km  is  reached,  a  quantity  which  is  decidedly  larger  than  would  be  expected  from  errors  of  measure- 


114     AN  INVESTIGATION   OP  THE  ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC  METHODS. 


ment  alone,  even  though  it  has  been  found  that  such  errors  are  usually  greater  in  high  latitudes.  At  pres- 
ent! it  does  not  seem  possible  to  decide  whether  this  lack  of  agreement  is  due  to  a  real  variation  in  the  sun's 
rate  of  rotation,  to  the  presence  of  some  source  of  systematic  error  in  the  observations,  or  to  the  disturbing 
effect  of  proper  motions  in  the  sun's  reversing  layer.  I  am  inclined,  however,  to  ascribe  it  mainly  to  small 
systematic  errors  in  the  earlier  series  of  observations.  The  principal  sources  of  error  to  which  these  were 
subject  have  already  been  referred  to,  and  there  is  little  doubt  that  they  must  have  affected  the  results  to  some 
extent.  As  several  of  these  difficulties  were  eliminated,  or  their  effect  much  reduced,  in  the  later  series  of 
observations,  and  as  the  check  by  means  of  the  exposure  on  the  sun's  pole  was  available  in  the  later 
results,  it  is  highly  probable  that  the  greater  part  of  the  difficulty  is  to  be  looked  for  in  the  earlier  series. 
If  such  is  the  case,  the  single  most  serious  cause  of  error  is  probably  the  astigmatism  of  the  sun's  image. 

The  influence  of  proper  motion  in  the  reversing  layer  may  be  very  appreciable  in  its  effect  upon  the 
values  of  the  solar  rotation,  and  it  is  possible  that  this  cause  may  be  in  part  accountable  for  the  discrepan- 
cies between  the  two  series  of  results.  As  will  be  shown  in  another  place,  proper  motions  amounting  to  as 
much  as  0.2  km  have  been  found  in  a  disturbed  region  in  the  neighborhood  of  spots,  and  of  course  it  is 
highly  probable  that  motions  of  smaller  amount  are  present  frequently.  The  probability  of  their  occur- 
rence in  high  latitudes,  however,  would  appear  to  be  less  than  in  the  zones  of  chief  spot  activity. 

There  seem  to  be  three  main  arguments  against  the  conclusion  that  these  results  indicate  an  actual 
variation  in  the  sun's  period  of  rotation.  The  first  of  these  is  that  the  variation,  if  present,  seems  to  be 
confined  to  the  higher  latitudes.  It  would  certainly  appear  probable  that  such  an  effect  would  be  marked 
in  the  zones  of  greatest  spot  activity,  between  10°  and  30°  of  latitude,  and  differences  in  these  zones  were 
found  by  Halm  (9)  in  the  series  of  observations  from  which  he  concluded  the  existence  of  such  a  variation. 
On  the  other  hand,  the  values  given  here  indicate  essentially  no  difference  for  the  years  1906-1907  and  1908 
between  o°  and  40°  of  latitude.  We  have  seen,  however,  that  all  of  the  spectrum  lines  which  show  abnormal 
values  of  the  rotational  velocity,  such  as  those  of  cyanogen,  lanthanum,  calcium,  and  hydrogen,  appear  to 
give  the  largest  deviations  from  the  normal  values  in  the  higher  latitudes.  Accordingly,  the  existence  of  a 
variation  in  the  sun's  rate  of  rotation  which  is  confined  to  high  latitudes  is  perhaps  less  anomalous  than 
might  at  first  appear. 

A  second  argument  against  the  occurrence  of  a  variation  in  the  sun's  rotation  period  is  the  close  agree- 
ment of  the  results  given  here  for  1908  with  Duner's  values  obtained  from  observations  extending  through 
six  years,  from  1887  to  1889  and  from  1899  to  1901.  A  comparison  of  the  1906-1907  and  1908  observa- 
tions with  those  of  Duner  for  the  six  latitudes  employed  by  him  gives  the  results  in  Table  25,  the  values 
being  obtained  in  all  cases  from  the  corresponding  empirical  formulas. 

TABLE  25.  —  COMPARISON  OF  THE  RESULTS  WITH  THOSE  or  DUNER. 


1906-1907 

1908 

DUNER. 

0 

,  +  ,, 

£ 

,  +  ,, 

« 

,+., 

* 

0 

km 
2.06 

14.62 

km 

2.05 

14-54 

km 
2.08 

14.81 

IS 

1.96 

14.38 

i-95 

14-32 

1.97 

14-53 

3° 

1.67 

13.66 

1.66 

13.61 

1.67 

13.76 

45 

1.27 

12.77 

1.26 

12.64 

1.26 

12.70 

60 

0.8S 

12.  IO 

0.82 

11.67 

0.82 

11.65 

75 

0.44 

12.  OO 

0.40 

10.96 

0.40 

10.88 

The  agreement  of  the  1908  observations  with  those  of  Duner  is  remarkably  close  on  the  average.  This 
is  especially  true  in  the  higher  latitudes,  the  very  region  in  which  the  probability  of  a  variation  in  the 
rotation  period  is  mainly  in  question.  Accordingly,  we  may  conclude  that  the  evidence  furnished  by  this 
comparison  is  decidedly  against  the  existence  of  such  a  variation. 


COEFFICIENTS   OF   FAYE's    FORMULA. 


In  a  discussion,  however,  advocating  the  existence  of  a  variation  in  the  sun's  rate  of  rotation,  Halm 
maintains  that  Duner's  observations  themselves  furnish  evidence  of  such  a  variation  (9),  with  a  period  of 
about  three  years.  In  comparing  the  Edinburgh  and  Upsala  results,  Halm  has  made  use  of  Faye's  formula 

v  +  z>i  =  (a  —  b  sin2  </>)  cos  <j> 

connecting  the  rotational  velocity  with  the  heliographic  latitude.     In  this  form,  as  will  be  shown  later, 
the  1908  observations  give 

v  +  vl  =  (2.053  ~~  o-546  sin2  <f>)  cos  <#> 

Table  26  contains  the  values  obtained  by  Halm  for  the  coefficients  a  and  b,  with  the  Mount  Wilson 
values  added  for  comparison. 

TABLE  26.  —  COEFFICIENTS  OF  THE  FA  YE  FORMULA. 


OBSERVATIONS. 

DATE. 

a 

b 

Upsala      .... 

1899.5 

1.98 

0-57 

1900-5 

2.  II 

O.4O 

1901.5 

2.O9 

0.79 

Edinburgh    .     .     . 

1901.7 
1902.5 
I903-S 

2.O6 

1-973 
2.036 

O.7O 
0.560 
0.251 

1904-5 

2.075 

O.27I 

IQOS-S 
1906.3 

2.039 

2.OIO 

0-245 
0.294 

Mount  Wilson  .     . 

1907.0 
1908.5 

2-055 
2-053 

0.480 
0.546 

The  Faye  formula,  as  will  appear  later,  does  not  fully  satisfy  the  1906-1907  observations,  but  the 
approximation  is  sufficiently  close  for  the  purposes  of  this  comparison. 

On  the  basis  of  a  three-year  period,  with  a  minimum  near  1902.5,  it  is  evident  that  1908.5  should  also 
give  a  minimum  value  of  a.  Actually,  however,  it  is  nearly  equal  to  the  largest  value  obtained  by  Halm 
between  1901  and  1906.  Moreover,  the  value  of  a  for  1907.0  is  practically  identical  with  that  for  1908.5, 
and  decidedly  larger  than  Halm's  value  for  the  neighboring  epoch  1906.3.  Similarly,  the  Mount  Wilson 
values  of  b  are  much  larger  than  would  be  expected  from  comparison  with  the  Edinburgh  results,  and  are 
decidedly  opposed  to  the  idea  of  a  periodic  variation  in  this  quantity. 

A  third  main  objection  to  the  conclusion  that  a  real  variation  of  the  rotation  period  is  indicated  by  the 
differences  between  the  results  obtained  from  the  two  series  of  observations  is  closely  connected  with  the 
preceding.  It  is  the  fact  that  the  1908  observations  are  well  represented  by  Faye's  formula,  while 
the  1906-1907  results  show  systematic  discordances  of  such  size  as  to  necessitate  the  use  of  an  additional 
constant  in  the  equation.  Since  the  results  of  Duner  and  the  mean  values  obtained  by  Halm  are  well 
represented  by  this  formula,  and  it  has  additional  support  in  the  observations  of  the  rotation  period 
of  sun-spots,  it  seems  improbable  that  the  discordances  given  by  the  earlier  series  of  observations  can 
be  other  than  inherent  in  the  results  themselves.  This  is  indicated  by  the  discussion  that  follows. 

A  solution  of  the  1906-1907  results  by  least  squares,  weighting  the  observations  according  to  their 
number,  gives  the  following  form  of  Faye's  equation  : 

v  +  Vi  =  (1.575  +  0.480  cos2  <£)  cos  <f> 

This  equation  gives  the  residuals  which  appear  in  the  third  column  of  Table  27,  the  differences  being 
observed  —  computed. 


Il6      AN  INVESTIGATION   OF  THE   ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC  METHODS. 
TABLE  27.  —  REPRESENTATION  OF  THE  1906-1907  OBSERVATIONS  BY  EMPIRICAL  FORMULAE. 


I 

II 

WEIGHT. 

*.  +  .,) 

AB 

0.2 

21 

km 
+  O.Oig 

km 
+  O.OIO 

0 

+  O.IO 

7-7 

IS 

O.OOO 

—  0.007 

-  0.03 

15.0 

24 

+  0.003 

+  O.OOI 

+  0.03 

22.7 

13 

—  O.OlS 

—  0.014 

—  O.II 

29.8 

24 

-  0.005 

+  0.005 

+  O.O2 

37-8 

16 

—  O.O2I 

—  0.008 

—  O.IO 

44.6 

23 

—  O.OII 

O.OOO 

-  0.03 

52.7 

18 

—  O.OOI 

+  0.004 

+  0.02 

59-6 

24 

+  0.009 

+  0.005 

+  0.03 

65.6 

20 

+  O.OIO 

—  O.OO2 

o.oo 

75-i 

33 

+  O.O2I 

O.OOO 

+  0.07 

80.4 

ii 

+  0.014 

—  0.008 

—  0.21 

The  residuals  under  I  are  so  clearly  systematic  in  character  as  to  necessitate  the  addition  of  a  term  in 
cos2  (/>.  A  solution  by  least  squares  with  the  inclusion  of  such  a  term  gives  the  equation 

v  +  v^  =  (1.791  —  0.621  cos  </>  +  0.894  cos2  <£)  cos  </> 
The  corresponding  equation  for  the  angular  velocity  is 

£  =  i2°43  -  3°48  cos  <j>  +  5?68  cos2  </> 

The  equations  for  v  +  •vl  and  £  are  derived  independently  and  so  are  not  convertible  into  one  another  by  a 
substitution.  These  equations  give  the  residuals  under  II  in  Table  27,  which  evidently  are  not  systematic 
in  character.  A  similar  solution  for  the  1908  observations  indicates  that  these  are  satisfied  by  the  Faye 
equation  with  sufficient  accuracy.  The  formulae  in  this  case  are  found  to  be 

v  +  Oj  =  (1.507  +  0.546  cos2  <£)  cos  ((>  %  =  io°57  +  4?O4  cos2  <£ 

The  corresponding  residuals  are  shown  in  Table  28. 

In  the  highest  latitudes  the  angular  velocity  changes  very  rapidly  with  the  linear,  which  of  course 
accounts  for  the  large  value  of  the  discordance  in  £  at  79.  i.  This  point  is  of  low  weight.  The  residual  at 
44?8  is  surprisingly  large  for  a  point  of  such  high  weight.  In  view  of  the  simple  character  of  the  formula, 
however,  the  size  of  the  residuals  is  in  general  entirely  satisfactory. 

A  comparison  of  the  last  formula  with  the  corresponding  equations  of  Duner  and  Halm  will  be  of 
interest.  These  are  as  follows  : 

Duner          .     .     .     £  =  10.60  +  4.21  cos2  $ 

Halm      .     .     .     .     £  =  12.03  +  2.50  cos2  ^ 

Adams  (1908)  .     .     £  =  10.57  +  4-°4  cos2  <£ 

The  agreement  of  the  first  term  in  the  formulae  of  Duner  and  myself  is  remarkable,  but  probably  is 
somewhat  accidental.  It  represents,  of  course,  the  angular  velocity  of  rotation  at  the  sun's  pole,  and 
corresponds  to  a  rotation  period  of  34.0  days. 

In  addition  to  solving  each  series  of  observations  separately,  I  have  obtained  a  mean  result  for  the  two 
sets  by  combining  the  values  for  closely  adjoining  points  of  latitude  and  solving  these  values  by  least  squares 
with  an  equation  of  Faye's  form.  Equal  weights  have  been  assigned  to  the  two  series  in  the  formation  of 
the  means  and  the  values  then  weighted  in  the  solution  according  to  the  number  of  observations.  The 
results  are  as  follows : 

j)  +  v1  =  (1.550  +  0.501  cos2  <£)  cos  <f>  |  =  n°o4  +  3°5o  cos2  $ 


PROBABLE  ERRORS. 


117 


Table  29  contains  the  values  on  which  the  solution  is  based,  and  the  residuals  (observed  —  computed) 
which  are  given  by  these  two  formulae.  These  residuals  are  small  in  amount,  and  there  appears  to  be  no 
tendency  to  systematic  effect  in  sign.  This  result  evidently  is  due  largely  to  the  smoothing-out  effect  of 
the  1908  observations. 


TABLE  28. —  REPRESENTATION  OF  1908  OBSERVATIONS 
BY  FAYE'S  FORMULA. 


TABLE  29. —  REPRESENTATION  OF  MEAN  RESULTS  FOR 
1906-1907  AND  1908  BY  FAYE'S  FORMULA. 


<t> 

WEIGHT. 

A(»  +  *,) 

A£ 

0.4 

21 

km 
+  O.OOg 

+  0-03 

4.1 

IS 

-  0.005 

—  0.06 

II.  2 

12 

—  0.002 

—  0.06 

14.9 

18 

—  O.OO5 

—  0.06 

IQ.2 

14 

—  0.016 

-0.13 

29.8 

16 

+  0.004 

+  o  04 

34-1 

IS 

0.000 

+  0.01 

44-8 

i? 

+  0.023 

+  0.28 

49.6 

16 

+  O.OII 

+  0.18 

60.  i 

22 

—  0.012 

-0.08 

65.0 

17 

—  O.OO6 

—  O.OI 

75-° 

17 

—  O.OO3 

+  O.O2 

79.1 

7                —  0.016 

—  0.46 

i 

, 

,  +  ,, 

A(*  +  V 

* 

» 

km 

km 

0 

0.3 

2.068 

+  O.OI7 

+  0.13 

7.6 

2.019 

—  0.004 

—  O.O2 

i  S-o 

•95° 

+  O.OOI 

+  O.O2 

20.9 

•839 

—  O.OI7 

—  O.I2 

29.8 

.672 

—  O.OOI 

O.OO 

35-9 

•5°9 

—  O.OII 

—  O.I  I 

44-7 

.285 

+  0.004 

+  0.03 

Si-2 

.099 

+  0.003 

+  O.O2 

59-9 

0.836 

—  0.005 

—  O.O9 

6S-3 

0.683 

—  O.OOI 

—  O.O4 

7S-o 

0.416 

+  0.008 

+  0.17 

79.8 

0.275 

-  0.003 

—  O.I4 

14.    PROBABLE  ERRORS. 

A  comparison  of  the  probable  errors  of  the  results  of  these  determinations  with  the  visual  observations 
of  Duner  and  Halm  is  rendered  rather  difficult  by  the  inherent  difference  in  the  nature  of  the  methods 
employed.  The  photographic  results  are  based  upon  the  measurement  of  a  considerable  number  of  lines, 
the  mean  values  of  which  are  combined  to  give  a  single  determination  of  the  rotational  velocity.  In  the 
work  of  Duner  and  Halm  only  two  lines  were  used,  but  from  eight  to  twelve  settings  of  the  micrometer 
wire  were  made  upon  each  line.  In  the  case  of  the  photographic  determinations  four  settings  were  made 
in  each  position  of  the  plate  under  the  measuring  microscope.  It  will  be  sufficient  for  general  purposes  to 
compare  the  probable  error  for  a  single  line  on  the  photographic  plate  with  the  probable  error  for  a  single 
visual  determination,  taken  from  a  series  equal  in  number  to  the  lines  on  the  photographic  plate.  This 
should  give  a  marked  advantage  to  the  visual  results,  since  the  mean  of  two  lines  is  used,  and  a  large  num- 
ber of  settings  employed  on  each  of  them.  In  the  case  of  the  photographic  observations,  however,  such  of 
the  lines  as  give  marked  systematic  deviations  should  evidently  be  omitted  when  the  probable  error  is 
formed.  Accordingly,  six  lines  of  this  sort,  the  behavior  of  which  has  already  been  fully  discussed,  namely, 
*•  4196,  X  4197,  X  4216,  \  4257,  X  4266,  and  X  4290.38,  are  left  out  of  consideration.  This  leaves  a  total  of 
fourteen  lines  for  the  1906-1907  series  and  sixteen  for  the  1908  series.  Plates  taken  at  random  from  each 

set  give  the  following  values  : 

SINGLE  LINE.  MEAN  VALUE  FROM  PLATE. 

1006-1907 r  =  ±  0.015  km  ro=  ^  0.004  km 

1908 r  =  i  0.009  ro =  -*-  0.002 

A  series  of  determinations  by  Halm  in  1903  (s)  averaging  fifteen  observations  for  each  latitude  give 

r  =  ±  0.070  km  r 0  —  ±  0.018  km 

The  earlier  series  of  observations  by  Duner  show  probable  errors  about  twice  as  large  as  those  of  Halm, 
but  for  the  completed  series  no  values  are  given,  though  they  are  undoubtedly  considerably  smaller  than 
for  the  previous  results.  It  should  be  noted  that  the  photographic  observations  show  somewhat  larger 
probable  errors  in  the  higher  latitudes. 


Il8        AN  INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


A  comparison  of  these  values  indicates  a  marked  gain  in  the  degree  of  accuracy  of  the  photographic 
results  over  the  visual.  It  is  of  course  impossible  to  state  how  much  of  this  gain  is  due  to  the  more  pow- 
erful spectroscopic  apparatus  and  the  larger  solar  image  employed,  and  how  much  to  the  use  of  the 
photographic  method,  but  it  seems  probable  that  both  facts  contribute  materially  to  the  result. 

15.    COMPARISON  OF  RESULTS  FOR  SUN-SPOTS,  FACUL/E,  FLOCCULI,  REVERSING  LAYER, 
THE  a  LINE  OF  HYDROGEN,  AND  \4227  OF  CALCIUM. 

At  the  conclusion  of  this  discussion  of  the  rotation  of  the  sun  as  determined  from  the  displacements  of 
the  lines  in  the  reversing  layer,  it  seems  desirable  to  add  a  comparison  with  the  values  obtained  by  various 
observers  from  sun-spots,  faculae,  and  hydrogen  and  calcium  flocculi.  Such  a  comparison  with  the  reversing 
layer  results  of  Duner  and  Halm  has  already  been  made  by  Hale  and  Fox  in  their  discussion  of  the  motion 
of  the  calcium  flocculi  (19),  and  by  Hale  in  his  paper  on  the  motion  of  the  hydrogen  flocculi  (20).  In 
view  of  the  additional  material  now  available  for  the  reversing  layer,  a  repetition  of  these  values  will  not 
be  out  of  place.  The  quantities,  which  are  given  in  Table  30,  are  derived  from  empirical  formulas  where 
these  have  been  obtained ;  in  other  cases  they  are  taken  from  curves  or  found  by  interpolation  from  the 
original  observations.  In  the  case  of  the  work  of  Carrington,  Spoerer,  and  Maunder  on  sun-spots,  Duner 
and  Halm  on  the  reversing  layer,  and  Adams  on  the  reversing  layer,  Ha  and  X  4227,  empirical  formula? 
are  available.  In  the  form  employed  for  calculation  they  are  as  follows : 


Carrington       

Spoerer 

Maunder 

Duner 

Halm 

Adams  (mean  of  two  series) £  =  11.04  +  3-5°  cos2  4> 

Adams  \  4227 £=  12.5    +2.4    cos2  <£ 

Adams  H a       £  =  13.6    +  1.4    cos2  <j> 

TABLE  30.  —  COMPARISON  OF  ROTATION  RESULTS  FROM  VARIOUS  SOURCES. 


=  14.42  -  2.75  sin? 

=  8.55  +  5.80  cos  i 

=  12.43  +  2-CI  cos2 ' 

=  10.60  +  4.21  cos2  ' 

=  12.03  +  2-S°  cos2 ' 


<t> 

SUN-SPOTS. 

FACUL.E. 
STRATO- 

NOFF. 

CALCIUM  FLOCCULI. 

HYDRO- 
GEN 
FLOC- 
CULI. 

REVERSING  LAYER. 

X4227 

ADAMS. 

Ha 
ADAMS. 

CARRING- 

TON. 

SPOERER. 

MAUN- 
DER. 

HALE 
AND  Fox 
(KEN- 
WOOD). 

Fox. 

HALE, 
MOUNT 
WILSON. 

MOUNT 
WILSON. 

DUNER. 

HALM. 

ADAMS, 
Two 
SERIES. 

0 

S 

IO 

15 

20 

25 

3° 
3S 
40 

45 
SO 

SS 
60 

6S 
70 
75 

14.42 
14-38 
14.29 
14.16 
14.00 
13.81 
13.60 
I3-38 

H-35 
14-32 
14.26 

I4-I5 
14.00 
13.80 
13-57 
I3-30 

14.44 

14-43 
14.38 

14-3° 
14.19 
14.06 
13-91 
13-74 

14.62 
14.61 
14.46 

14-24 
14.18 
14.14 
13.84 

14.70 

14-59 
14.44 
I4-30 
14.17 
14.02 
I3-83 

I4-52 
14.46 

14-33 
14.09 
13.80 
13.82 
I3-83 

14.42 
14.38 
14.32 
14.28 
14.27 
14.17 
13.98 
14.04 
13.92 

14.6 

14.81 
14.78 
14.68 

14-53 
14.32 
14.06 
I3-76 
13.42 

13-07 
12.70 
12.34 
11.99 
11.65 

11-35 
11.09 
10.88 

14-53 

14.50 
14.46 
14-37 
14-24 
14.09 
13.90 
I3-70 
13-50 
13.28 

13-07 
12.86 
12.66 
12.48 
12.32 

12.20 

H-54 
14-51 
14-43 
14-31 
14-13 
13-91 
13-67 
13-39 
13.09 
12.79 
12.49 
12.19 
11.92 
11.67 

11-45 
11.27 

14.9 
14.8 
14-3 
13-7 
I3-I 
12.7 

iS-o 
14.9 
14.6 
H-3 
13-9 
13-7 

SUMMARY   OF   ROTATION   RESULTS. 


As  has  already  been  stated,  my  own  1908  observations  agree  closely  with  Duner's  in  the  higher  lati- 
tudes, but  are  smaller  and  nearer  Halm's  values  in  the  lower  latitudes.  In  Table  31  I  have  taken  simple 
means  for  the  spot  and  flocculi  results  and  compared  them  with  the  values  obtained  from  my  two  series  of 
observations  on  the  reversing  layer.  They  are  shown  graphically  in  Fig.  2. 

TABLE  31.  —  SUMMARY  or  ROTATION  RESULTS  FROM  VARIOUS  SOURCES. 


0 

SPOTS. 

FACUL.S. 

FLOCCULI. 

REVERSING 
LAYER. 

O 

0 

14.40 

14.62 

H-55 

o 

14-54 

5 

14.38 

14.61 

14.48 

14-51 

10 

I4-3I 

14.46 

14-36 

14-43 

15 

14.20 

14.24 

14.22 

14-31 

20 

14.06 

14.18 

14.08 

14-13 

25 

13.89 

14.14 

14.00 

i3-9i 

30 

13.69 

13.84 

13.88 

13-67 

35 

13-47 

13.81 

13-39 

Faculae 
Reversing  layer 
Ca  Flocculi  - 
Sun  spots 


14.6 


14.4 


I4TZ 


14.0 


13.8 


13.6 


13.4 


I3.E 


13.0 

0°       <$>         5°  10°  15°  Z0°  ZS°  30°  35"  40° 

FIG.  2. —  Curves  showing  the  values  of  the  angular  velocity  obtained  from  observations  of  sun-spots, 
faculae,  calcium  flocculi,  and  reversing  layer.    Plotted  from  the  results  given  in  Table  31. 


I2O     AN  INVESTIGATION  OF   THE  ROTATION  PERIOD   OF  THE   SUN  BY   SPECTROSCOPIC  METHODS. 

Attention  has  already  been  called  by  Mr.  Hale  to  the  comparatively  small  values  of  the  angular  veloc- 
ity given  by  spots  (19).  The  difference  at  the  equator  amounts  to  o?2  as  compared  with  facuke.  flocculi,  or 
reversing  layer,  and  in  view  of  the  close  accordance  of  the  spot  observations  at  this  latitude  the  result  is 
probably  to  be  considered  as  genuine.  Similar  differences,  as  compared  with  faculae  and  flocculi,  are  shown 
in  higher  latitudes  by  the  results  of  Carrington  and  Spoerer,  but  the  inclusion  of  Maunder's  larger  values 
in  the  mean  conceals  this  effect.  There  seems  to  be  a  tendency  for  the  reversing  layer  to  give  slightly  larger 
values  than  the  flocculi  between  latitudes  o°  and  20°.  This  may  be  due,  as  Mr.  Hale  has  suggested  in  his 
discussion,  to  the  possibility  that  the  faculse  and  flocculi  retain  the  velocities  of  the  lower  levels  from 
which  they  rise,  but  the  differences  are  small  and  hardly  sufficient  to  warrant  a  definite  conclusion,  espe- 
cially in  view  of  the  considerable  discordance  among  the  separate  flocculi  determinations. 

Another  most  interesting  consideration  is  whether  there  appears  to  be  any  difference  in  the  law  of  the 
equatorial  acceleration  in  the  results  given  by  the  observations  of  the  various  objects  on  the  sun's  surface. 
This  is  made  especially  important  by  the  discovery  of  the  remarkable  differences  in  velocity  shown  by 
spectroscopic  observations  of  the  hydrogen  lines  Ha  and  X  4227  of  calcium,  as  well  as  observations  of  the 
hydrogen  flocculi  with  the  spectroheliograph.  Unfortunately,  the  results  for  both  facuke  and  flocculi  are 
necessarily  very  uncertain  above  30°  of  latitude.  Accordingly,  in  order  to  secure  as  accurate  a  comparison 
as  seems  possible  with  the  material  available,  I  have  reduced  the  results  for  faculse,  flocculi,  Ha,  and  X  4227, 
by  a  least-squares  solution  of  Faye's  formula,  and  plotted  the  corresponding  results  for  every  5°  of  latitude. 
The  values  for  the  reversing  layer  are  from  the  formula  representing  the  combined  values  of  the  two  series 
of  observations.  A  difference  in  the  rate  of  change  of  angular  velocity  with  the  latitude  will  be  indicated 
by  a  lack  of  parallelism  in  the  resulting  curves,  and  in  order  to  show  this  more  clearly  the  values  have  all 
been  reduced  to  the  common  origin  of  i4?5o.  This  necessitates  the  addition  of  constant  quantities  to  the 
sun-spot  results  and  the  subtraction  of  constant  quantities  from  the  other  results.  The  comparison  is 
shown  graphically  in  Fig.  3.  One  extrapolation  has  been  made  for  the  faculce  and  the  flocculi. 

The  inspection  of  these  results  is  of  interest  in  many  ways.  The  spots  and  the  faculae  give  values  which 
are  practically  identical  throughout,  a  result  which  is  to  be  expected  from  the  close  relation  of  these  objects 
to  the  solar  photosphere.  Intermediate  between  these  and  the  flocculi  is  X  4227,  which  shows  notably  less 
equatorial  acceleration.  The  calcium  flocculi  show  still  less,  and  Ha  the  least  of  all,  the  differences  in  its 
case  being  very  great  indeed.  Apart  from  the  reversing  layer  these  results  are  quite  in  harmony  with 
the  commonly  accepted  views  of  the  relative  heights  of  the  various  gases  in  the  sun's  atmosphere.  The 
calcium  flocculi,  due  to  the  bright  reversals  of  the  calcium  lines  H  and  K,  are  usually  assumed  to  lie  at  a 
considerable  distance  above  the  sun's  photosphere,  and  probably  at  a  higher  level  than  the  material  producing 
the  blue  line  of  calcium  X  4227.  Similarly,  Ha,  which  rises  to  a  very  great  height  in  the  solar  atmosphere, 
gives  in  addition  to  very  large  absolute  velocities  a  greatly  reduced  amount  of  equatorial  acceleration. 
In  other  words,  these  results  are  all  satisfied  by  a  law  of  increase  of  angular  velocity  and  decrease  of  equa- 
torial acceleration  with  increasing  altitude  above  the  sun's  surface. 

For  the  reversing  layer  the  case  is  very  different,  however.  Here  the  rate  of  change  of  velocity  with 
latitude  is  the  most  rapid  of  any  observed,  a  result  which  on  the  basis  of  the  reasoning  given  above  would 
require  that  the  reversing  layer  lie  below  the  level  of  sun-spots  and  faculae.  This  almost  certainly  can  not 
be  the  case,  since  the  spectrum  of  faculae,  and  probably  of  spots,  gives  evidence  of  the  presence  of  the  ordi- 
nary reversing-layer  spectrum.  At  present  there  is  no  adequate  explanation  for  this  apparent  anomaly, 
but  a  suggestion  is  furnished  by  Wilsing's  theoretical  discussion  of  the  law  of  the  sun's  rotation  (21),  a 
memoir  the  bearing  of  which  on  the  motion  of  the  strata  above  the  reversing  layer  has  been  referred  to  by 
Mr.  Hale  (23).  In  the  course  of  this  discussion  Wilsing  arrives  at  the  conclusion  that  owing  to  internal 
friction  a  surface  is  reached  in  passing  toward  the  center  of  the  sun  at  which  essentially  uniform  angular 
velocity  is  attained.  Similarly,  above  the  solar  photosphere  another  surface  of  uniform  velocity  is  found, 
and  between  these  two  surfaces  the  motion  is  compared  by  Wilsing  to  that  of  "a  stream  flowing  between 


COMPARISON   OF   ANGULAR   VELOCITIES. 


121 


two  fixed  banks."  On  this  basis  it  is  evident  that  there  would  be  a  region  at  which  the  rate  of  change 
of  angular  velocity  with  latitude  would  be  a  maximum,  and  that  on  either  side  of  this  region  the  change 
would  become  less.  Accordingly,  if  we  may  assume  that  the  reversing  layer  corresponds  to  this  region  of 
most  rapid  change,  we  may  expect,  on  the  one  hand,  the  spots  and  faculae,  which  are  nearer  one  of  the  sur- 
faces of  uniform  velocity,  and,  on  the  other  hand,  X.  4227,  the  calcium  flocculi,  and  Ha,  whose  level  is  nearer 
the  other  surface,  to  give  less  equatorial  acceleration,  the  amount  diminishing  in  the  order  named.  The 
whole  question  is,  however,  extremely  complex,  the  quantities  concerned  are  small,  except  in  the  case  of 
Ha,  and  the  difficulties  involved  in  the  explanation  of  the  differences  in  the  values  of  the  absolute  velocities 
of  rotation  are  correspondingly  great.  It  will  hardly  be  profitable  to  continue  the  discussion  further  until 
additional  observational  material  has  placed  the  reality  of  these  differences  upon  a  more  certain  basis. 


14.6 


14.4 


14.2 


14.0 


Ha  at  limb 
Ca  Flocculi 
X  4-ZZ7 

Sun  spots 
Faculae 


Reversing  layer 


13.8 


13.0 


0?       <t> 


5? 


15°  aO?  25?  30°  35!  4-0?  45! 

FIG.  3.  —  Curves  showing  variation  of  angular  velocity  with  latitude  for  sun-spots,  facute,  calcium  flocculi,  reversing 
layer,  X  4227,  and  Ha..  To  facilitate  comparison  the  curves  are  all  reduced  to  the  common  origin  of  I4!so. 
Differences  in  the  amount  of  equatorial  acceleration  are  indicated  by  lack  of  parallelism  in  the  curves. 


122      AN  INVESTIGATION   OF   THE   ROTATION   PERIOD   OF   THE   SUN   BY   SPECTROSCOPIC   METHODS. 


16.    A  CASE  OF  LARGE  PROPER  MOTION  IN  THE  REVERSING  LAYER. 

Reference  was  made  at  an  earlier  point  in  this  discussion  to  the  disturbing  effect  of  proper  motions 
in  the  reversing  layer  upon  determinations  of  rotational  velocity.  Such  motions  have  frequently  been 
observed  in  the  neighborhood  of  sun-spots,  particularly  across  the  faculae  bordering  the  penumbra,  but 
it  appears  from  the  observations  described  below  that  they  may  extend  to  great  distances  from  spots 
as  well. 

On  September  15,  1908,  two  spots  of  considerable  size  were  nearing  the  west  limb  of  the  sun.  The  larger 
of  the  two  spots  was  at  11°  north  latitude,  the  other  at  6°  south  latitude.  Photographs  taken  with  the 
spectroheliograph  through  the  a  line  of  hydrogen  had  shown  both  spots  to  be  surrounded  by  immense 
regions  of  disturbance,  with  the  filaments  nearest  the  spots  giving  some  evidence  of  vortical  motion.  Ob- 
servations made  by  Mr.  Hale  during  the  passage  of  the  spots  across  the  sun's  disk  had  indicated  opposite 
directions  of  polarization  for  the  components  of  the  double  lines  in  the  spot  spectra,  thus  pointing  to  oppo- 
site directions  of  rotation  in  the  two  spots,  provided  vortical  motion  were  involved.  The  region  between 

TABLE  32.  —  OBSERVATIONS  or  PROPER  MOTION  IN  THE  REVERSING  LAYER. 
Plate  w  173.     1908,  Sept.  15,  6h  5™  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.5  mm.     Quality,  good. 


p-p 


seci 


o 

I72-5 

12.8 

14.7 

75-3 

29.6 

1.150 

0-0 

98.0 

26.4 

27.2 

62.8 

14.4 

1.012 

p 

-24.4 

44-8 

45-3 

44-7 

10.  1 

1.016 

D 

7-2 

59-9 

60.2 

29.8 

8.3 

I.OIO 

Diameter 

170.6  mm 

74-9 

75-i 

14.9 

7-4 

1.008 

Factor 

1.018 

89.9 

90.0 

o.o 

7.2 

1.008 

0  = 

o°o 

i 

*  = 

.* 

0  = 

^ 

X 

A 

V 

.  +  ,, 

£ 

A 

• 

,  +  ., 

t 

A 

• 

.  +  ,, 

s 

4208.766 

0.165 

km 

1.805 

km 
1.942 

o 

13-79 

0.162 

km 

•775 

km 
.907 

14.01 

0.140 

km 
1-535 

km 

-655 

13-54 

4210.494 

0.165 

.805 

1.942 

13-79 

0.164 

•794 

.926 

14.14 

0.140 

1-535 

-655 

13-54 

4216.136 

0.162 

.770 

1.907 

13-54 

0.162 

.768 

.900 

13-95 

0.140 

1-533 

-653 

13-52 

4220.509 

0.163 

•779 

1.916 

13.60 

0.163 

-777 

.909 

14.02 

0.140 

1.531 

.651 

13.51 

4222.382 

0.165 

.798 

1-935 

13-74 

0.162 

.766 

.898 

13-94 

0.140 

1-530 

.650 

13.50 

4233.328 

0.164 

•775 

1.912 

13-57 

0.163 

.769 

.901 

13.96 

0.142 

i-54i 

.661 

13.59 

4236.112 

0.164 

•775 

1.912 

13-57 

0.163 

1.768 

.900 

13-95 

0.142 

i-S4i 

.661 

13.59 

4246.251 

0.165 

•783 

1.920 

13-63 

0.163 

1.766 

.898 

13-94 

0.140 

1.518 

.638 

13.40 

4250.287 

0.165 

.781 

1.918 

13.62 

0.161 

1.741 

1-873 

I3-76 

0.141 

1.528 

.648 

13.48 

4250.945 

0.164 

.770 

1.907 

13-54 

0.163 

1.762 

1.894 

I3-9I 

0.140 

i-Si? 

•637 

13.39 

4254.505 

0.167 

.802 

1-939 

13-77 

o.i  60 

1.729 

1.861 

I3-67 

0-137 

1.483 

.603 

13.11 

4257-815 

0.162 

•747 

1.884 

13-38 

0.163 

1.760 

1.892 

13.90 

0-139 

1-504 

1.624 

13.29 

0  = 

44?7 

0  = 

6* 

0  = 

75!3 

4208.766 

0.104 

.146 

.242 

12.41 

0.059 

0.660 

0.729 

11.32 

0.029 

0-363 

0-397 

II.  II 

4210.494 

0.104 

.146 

.242 

12.41 

0.058 

0.650 

0.719 

11.17 

0.028 

0-351 

0-385 

10.77 

4216.136 

0.105 

•155 

.241 

12.40 

0.059 

0.660 

0.729 

11.32 

0.028 

0-351 

0.385 

10.77 

4220.509 

0.106 

-163 

-250 

12.57 

0.058 

0.645 

0.714 

11.09 

0.028 

0-351 

0.385 

10.77 

4222.382 

0.104 

.142 

-238 

12.36 

0.059 

0.655 

0.724 

11.24 

0.030 

0-373 

0.407 

"•39 

4233.328 

0.107 

1.168 

.264 

12.62 

0.059 

0-655 

0.724 

11.24 

0.029 

0-359 

o.393 

II.OO 

4236.112 

0.107 

1.167 

.263 

12.61 

0.060 

0.665 

0-734 

11.40 

0.029 

0-359 

0-393 

II.OO 

4246.251 

0.105 

1.146 

.242 

12.40 

0.058 

0.644 

0-713 

11.07 

0.028 

0.346 

0.380 

10.63 

4250.287 

0.104 

I-I35 

1.231 

12.30 

0.058 

0.643 

0.712 

1  1.  06 

0.028 

0.346 

0.380 

10.63 

4250.945 

0.107 

1.165 

1.261 

12-59 

0.059 

0-653 

0.722 

II.  21 

0.029 

0-358 

0.392 

10.97 

4254.505 

0.106 

I-I54 

1.250 

12.48 

0.058 

0.642 

0.711 

11.04 

0.028 

0-345 

0-379 

10.60 

4257-815 

0.104 

1.131 

1.227 

12.26 

0.060 

0.663 

0.732 

"•37 

0.028 

0-344 

0-378 

10.58 

PROPER   MOTION   IN   THE   REVERSING   LAYER. 


123 


the  spots  was  in  an  extremely  chaotic  state,  owing  probably  to  the  intermingling  of  the  disturbances  cen- 
tered about  the  two  spots. 

Four  plates  of  the  region  of  the  spectrum  near  X  4227  were  taken  on  this  date  with  the  rotation  apparatus 
at  latitudes  ranging  from  o°  to  75°,  in  steps  differing  by  15°.  Accordingly,  for  one  of  the  settings  at  o°, 
a  point  6°  north  of  one  of  the  spots  fell  upon  the  slit  of  the  instrument ;  for  another,  at  latitude  i4?9,apoint 
4°  north  of  the  other  spot.  In  the  first  case  the  point  fell  considerably  east  of  the  spot  as  welt.  All  of  the 
plates  were  taken  in  connection  with  the  investigation  of  the  motionof  the  calcium  vapor  giving  rise  to  X  4227, 
and  their  density  was  made  greater  than  usual  in  order  to  facilitate  settings  upon  this  broad  and  hazy  line. 

As  soon  as  the  measurement  of  the  plates  was  begun,  it  was  found  that  the  values  at  latitudes  o°  and  14.9 
were  very  discordant,  when  compared  with  those  regularly  obtained.  Therefore  a  list  of  lines  suitable 
for  measurement  was  selected,  since  the  regular  list  could  not  be  used  on  account  of  the  great  density  of 
the  negatives,  and  the  plates  were  investigated  separately.  The  results  for  these  lines  are  shown  in  detail 
in  Table  32.  The  results  for  X4227  are  given  in  Table  33. 

TABLE  32. — OBSERVATIONS  OF  PROPER  MOTION  IN  THE  REVERSING  LAYER  —  Continued. 
Plate  <•>  174.     1908,  Sept.  15,  6h  sm  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.5  mm.     Quality,  good. 

[Plate  constants  are  the  same  as  for  u  173.] 


0  = 

o?o 

<t>  = 

I4!o 

</>  = 

29^8 

A 

f 

f  +  », 

(. 

A 

•c 

tl  +  Dj 

£ 

A 

i> 

»  +  ?, 

£ 

4208.766 

0.161 

km 
1.762 

km 
1.899 

13-47 

O.I  60 

km 
1-750 

km 
.882 

13-83 

0.140 

km 
1-543 

km 
1.663 

o 

13.60 

4210.494 

0.162 

1.772 

1.909 

13-55 

0.161 

1.761 

•893 

13-91 

0.141 

1-553 

I-673 

13.69 

4216.136 

0.161 

1-757 

1.894 

13-45 

0.162 

1.770 

.902 

13-97 

0.141 

1-543 

1.663 

13.60 

4220.509 

0.162 

1.766 

•903 

I3-5I 

o.i  60 

1-745 

.877 

13-79 

0.140 

1-530 

I-653 

13-52 

4222.382 

0.163 

1.776 

•913 

I3-58 

0.162 

.766 

.898 

13-94 

0.142 

•551 

1.671 

13-67 

4233-328 

0.162 

1.758 

.895 

13-45 

0.161 

•749 

.881 

13.82 

0.142 

•538 

1.658 

13-56 

4236.112 

0.162 

1-757 

.894 

13-44 

0.162 

•759 

.891 

13.89 

0.142 

•538 

1.658 

13-56 

4246.251 

0.162 

1-752 

.889 

I3.4I 

0.161 

-743 

.875 

13-77 

0.142 

•537 

I-657 

13-56 

4250.287 

0.161 

1.740 

.877 

13-33 

0.161 

.740 

.872 

'3-75 

0.140 

•515 

I-635 

13-38 

4250.945 

0.166 

1.794 

-931 

I3-7I 

0.162 

•749 

.881 

13.82 

0.141 

•525 

1.645 

13.46 

4254-505 

0.162 

1-749 

.886 

13-39 

o.i  60 

.729 

.861 

13-67 

0.142 

-536 

1.656 

13-55 

4257.815 

0.163 

I-758 

-895 

13-45 

0.162 

.748 

.880 

13-81 

0.141 

•525 

I-645 

13.46 

<t>  = 

44t7 

•/>  = 

62!8 

<t>  = 

75t3 

4208.766 

0.103 

I-I34 

1.230 

12.29 

0.059 

0.659 

0.728 

11.31 

0.030 

0-374 

0.408 

11.41 

4210.494 

O.IO2 

1.124 

1.220 

I2.I9 

0.059 

0.659 

0.728 

11.31 

0.030 

0-374 

0.408 

11.41 

4216.136 

0.105 

1.141 

1-237 

12.36 

0.059 

0.658 

0.727 

11.29 

0.030 

0-373 

0.407 

"-39 

4220.509 

0.103 

1.131 

1.227 

12.26 

0.060 

0.668 

0-737 

n-45 

0.030 

0-373 

0-407 

"•39 

4222.382 

O.IO4 

1.141 

1-237 

12.36 

0.060 

0.668 

0-737 

"•45 

0.030 

0-373 

0.407 

"•39 

4233-328 

0.103 

1.124 

I.22O 

12.19 

0.059 

0-654 

0.723 

11.23 

0.031 

0.380 

0.414 

11.58 

4236.112 

O.I  06 

I.I59 

1.255 

12-54 

0.060 

0.664 

0-733 

11.38 

0.032 

0-393 

0.427 

"•95 

4246.251 

0.103 

1.  122 

1.218 

12.17 

0.06  1 

0-675 

0-744 

11.56 

0.031 

0.380 

0.414 

11.58 

4250.287 

0.104 

I.I32 

1.228 

12.26 

0.060 

0.663 

0-732 

"•37 

0.029 

0-357 

0.391 

10.94 

4250.945 

0.105 

I.I4I 

1.237 

12.36 

0.060 

0.663 

0.732 

"•37 

0.029 

0-357 

0.391 

10.94 

4254-505 

0.105 

I.I4I 

1.237 

12.36 

0.059 

0.653 

0.722 

II.  21 

0.032 

0.392 

0.426 

11.92 

4257-815 

0.105 

I.I4I 

1.237 

12.36 

0.060 

0.663 

0-732 

"•37 

0.030 

0.369 

0.403 

11.27 

124     AN  INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC  METHODS. 


TABLE  32.  —  OBSERVATIONS  or  PROPER  MOTION  IN  THE  REVERSING  LAYER  —  Continued. 
Plate  10175.     1908,  Sept.  15,  7h  iom  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.5  mm.     Quality,  good. 

[Plate  constants  are  the  same  as  for  w  173.] 


0  =  0°0 

0  =  i4!g 

0  =  39:8 

A 

11 

.  +  »! 

f 

A 

V 

»  +  », 

« 

A 

V 

,-M, 

1 

km 

km 

0 

km 

km 

° 

km 

km 

0 

4208.766 

o.i  68 

1.836 

1-973 

14.01 

0.163 

1.785 

.917 

14.08 

0.141 

•547 

.      1.667 

13.64 

4210.494 

o.i  66 

1.815 

13.86 

0.164 

1.794 

.926 

14-15 

0.141 

•546 

1.666 

13.63 

4216.136 

0.166 

1.813 

1.950 

13.84 

0.163 

1.782 

.914 

14.06 

0.142 

•553 

I-673 

13.69 

4220.509 

0.166 

1.812 

1.949 

13.84 

0.164 

1.789 

.921 

14.11 

0.141 

•543 

1.663 

13.61 

4222.382 

o.i  68 

1.830 

1.967 

13.96 

0.164 

1.788 

.920 

14.10 

0.142 

•551 

1.671 

13.67 

4233-328 

0.167 

.813 

1.950 

13.84 

0.164 

1.782 

.914 

14.06 

0.142 

•546 

1.666 

13.63 

4236.112 

0.169 

.833 

1.970 

13.99 

0.165 

1.791 

•923 

14-13 

0.142 

•544 

1.664 

13.63 

4246.251 

0.172 

.855 

1.992 

14.14 

0.164 

J-774 

1.906 

14.00 

0.142 

•542 

1.662 

13.62 

4250.287 

o.i  66 

•794 

13-71 

0.163 

1.762 

1.894 

13.91 

0.142 

•539 

1.659 

13.57 

4250.945 

0.167 

•803 

1.940 

13-77 

0.164 

1.772 

1.904 

13.99 

0.142 

•537 

I-657 

13.56 

4254.505 

o.i  68 

-813 

1.950 

13.84 

0.164 

1.771 

1.903 

13.98 

0.143 

•546 

1.666 

13-63 

4257-815 

0.167 

.802 

1-939 

13.77 

0.165 

1.781 

1.917 

14.05 

0.142 

-536 

1.656 

13-55 

0  =  44?7 

0-62!8 

0  =  75?3 

4208.766 

O.IO2 

.123 

.219 

12.  18 

0.058 

0.650 

0.719 

ii.  17 

0.028 

0-349 

0-383 

10.72 

4210.494 

O.IOI 

•"3 

.209 

12.08 

0.060 

0.669 

0.738 

11.46 

0.027 

0-339 

0-373 

10.44 

4216.136 

O.IO2 

.122 

.218 

12.17 

0.059 

0.659 

0.728 

11.31 

0.028 

0-349 

0.383 

10.72 

4220.509 

O.IO2 

.121 

.217 

12.  l6 

0.058 

0.648 

0.717 

11.14 

0.027 

0-338 

0.372 

10.41 

4222.382 

0.102 

.120 

.216 

12.14 

0.058 

0.648 

0.717 

11.14 

0.028 

0.348 

0.382 

10.69 

4233-328 

0.103 

.121 

.217 

12.  l6 

0.059 

0-653 

0.722 

II.  21 

0.028 

0.346 

0.380 

10.63 

4236.112 

0.103 

.121 

.217 

12.  l6 

0.059 

0-653 

0.722 

II.  21 

0.027 

0.336 

0.370 

10.35 

4246.251 

O.IO2 

.no 

.206 

12.05 

0.058 

0.642 

0.711 

II.O4 

0.027 

0-335 

0.369 

10.32 

4250.287 

0.102 

.110 

.206 

12.05 

0.058 

0.642 

0.711 

11.04 

0.028 

0.346 

0.380 

10.63 

4250.945 

o  104 

.130 

.226 

12.24 

0.057 

0.632 

0.701 

10.89 

0.028 

0.346 

0380 

10.63 

4254.50S 

0.104 

.130 

.226 

12.24 

0.060 

0.663 

0.732 

n-37 

0.028 

0.346 

0.380 

10.63 

4257-815 

O.IO2 

.108 

.204 

12.03 

0-057 

0.630 

0.699 

10.86 

0.027 

0-335 

0.369 

10.32 

Plate  w  176.     1908,  Sept.  15,  7h  iom  G.  M.  T.     Measured  by  L.  on  T.     Distance  from  Limb  1.5  mm.     Quality,  good. 

[Plate  constants  are  the  same  as  for  u  173.] 


0  »  O°O 

0  =  I4?0 

0  =  2Q!8 

A 

V 

.  +  », 

f 

A 

V 

•  +  », 

t 

A 

V 

r  +  r, 

£ 

km 

km 

0 

km 

km 

o 

km 

km 

0 

4208.766 

0.166 

1.816 

1-953 

13.87 

0.163 

1.784 

1.916 

14.08 

0.142 

i-SSS 

1-675 

13-70 

4210.494 

0.165 

1.805 

1.942 

13.79 

0.163 

1.783 

1.915 

14.07 

0-143 

•565 

.685 

13-79 

4216.136 

o.i  66 

1.812 

1.949 

13.84 

0.163 

1.780 

1.912 

14.04 

0.142 

•553 

-673 

13.69 

4220.509 

o.i  66 

.811 

1.948 

13.83 

0.164 

1.789 

1.921 

14.11 

0.141 

•542 

.662 

13.60 

4222.382 

0.167 

.820 

1-957 

13.89 

0.163 

1.777 

1.909 

14.02 

0.142 

•551 

.671 

13-67 

4233.328 

o.i  66 

.803 

1.940 

13.77 

0.163 

-771 

I-903 

13.98 

0.142 

•544 

.664 

13.61 

4236.112 

0.167 

.809 

1.946 

13.82 

0.165 

.790 

1.922 

14.12 

0.142 

1-543 

•663 

13.61 

4246.251 

o.i  68 

.817 

1-954 

13.88 

0.163 

.768 

1.900 

13.96 

0-143 

1-552 

.672 

13.68 

4250.287 

o.i  68 

.816 

1-953 

13.87 

0.163 

.763 

1.895 

13-92 

0.142 

1-538 

.658 

13.56 

4250.945 

0.169 

.824 

1.961 

13.92 

0.164 

-771 

1.903 

13.98 

0.142 

1-537 

.657 

13.56 

4254.505 

o.i  68 

.813 

1.950 

13.85 

0.163 

•759 

1.891 

13.89 

0-143 

1.546 

1.666 

13.63 

4257.815 

0.167 

.802 

1-939 

13.77 

0.162 

1.748 

1.880 

13.81 

0.142 

I-536 

1.656 

13.55 

0  =  44?7 

0  =  62!8 

0  =  7S?3 

4208.766 

O.IO2 

•125 

1.  221 

12.  2O 

0.059 

0.662 

0-731 

"•35 

0.028 

0-351 

0.385 

10.77 

4210.494 

O.IO4 

.146 

.242 

12.40 

0.060 

0.672 

0.741 

11.51 

0.029 

0-363 

0-397 

II.  II 

4216.136 

0.103 

•134 

.230 

12.28 

0.060 

0.671 

0.740 

11.49 

0.030 

0-374 

0.408 

11.41 

4220509 

O.IO2 

.121 

.217 

12.  l6 

0.059 

0.660 

0.729 

11.32 

0.029 

0-359 

0-393 

II.OO 

4222.382 

O.IO2 

.I2O 

.216 

12.14 

0.060 

0.669 

0.729 

11.32 

0.028 

0.348 

0.382 

10.69 

4233.328 

0.103 

I.I27 

.223 

12.22 

0.059 

0.656 

0.725 

11.26 

0.029 

o.347 

0-381 

10.66 

4236.112 

0.103 

I.I26 

.222 

12.  2O 

0.058 

0.644 

0.7I3 

11.07 

0.030 

0-357 

0.391 

10.94 

4246.251 

O.IO2 

I.II4 

.2IO 

I2.O9 

0.058 

0.643 

0.712 

11.05 

0.028 

0.346 

0.380 

10.63 

4250.287 

0.103 

1.  121 

I.2I7 

12.  l6 

0.060 

0.663 

0.732 

"•37 

0.029 

0.346 

0.380 

10.63 

4250.945 

O.IO2 

i.  no 

1.  206 

12.05 

0.060 

0.662 

0-731 

"•35 

0.030 

0-356 

0.390 

10.91 

4254.505 

0.103 

I.I2O 

1.216 

12.15 

0.059 

0.652 

0.721 

11.20 

0.028 

0-345 

0-379 

10.60 

4257.815 

O.IO2 

I.  no 

1.  206 

12.05 

0.058 

0.642 

0.711 

11.03 

0.028 

0-345 

0-379 

1  0.60 

PROPER   MOTION   IN   THE   REVERSING   LAYER. 


125 


The  combination  of  these  results  gives  the  values  of  v  +  vv  shown  in  Table  33,  the  normal  values  in 
each  case  being  added  for  comparison.     The  latter  are  from  the  1908  observations. 

TABLE  33.  —  PROPER  MOTION  IN  THE  REVERSING  LAYER. 


REVERSING  LAYER. 

X4227 

DISTURBED. 

NORMAL. 

DISTURBED. 

NORMAL. 

0.0 

km 

1-930 

km 
2.063 

km 
2.OI 

km 

2.12 

14.9 

1.899 

1.944 

1.97 

2.O2 

29.8 

1.666 

1.669 

i-73 

1-75 

44-7 

1.240 

1.289 

i-3i 

1.36 

62.8 

0.724 

0.740 

0.84 

0.82 

75-3 

0.389 

0.387 

0.48 

0.49 

At  latitude  30°  and  above  that  point  it  is  seen  that  the  results  obtained  from  these  plates  agree  fairly 
well  with  the  normal,  although  the  differences  at  latitude  44^7  are  unusually  large.  At  i4°9,  however, 
there  is  a  difference  of  0.045  km  for  the  reversing  layer,  and  at  o°  a  difference  of  0.133  km,  the  values  given 
by  these  plates  being  the  smaller.  The  results  for  X  4227  are  very  similar.  In  other  words,  proper 
motions  of  the  reversing  layer  toward  the  observer  at  the  west  limb  of  the  sun  of  0.05  km  in  one  case  and 
0.13  km  in  the  other  are  indicated,  if  we  assume,  as  seems  altogether  probable,  that  the  entire  difference  is 
due  to  the  disturbances  near  the  west  limb.  The  direction  of  motion  at  the  first  of  these  points,  i4?9,  is  in 
accordance  with  what  would  be  expected  if  vortical  motion  occurred  in  the  northern  spot  in  the  direction 
indicated  by  polarization  observations  and  photographs  with  the  spectroheliograph.  These  point  to  a 
direction  of  motion  counter-clockwise  as  seen  from  above.  Accordingly,  at  a  point  north  of  this  spot, 
the  motion  would  be  toward  the  observer,  and  the  rotational  velocity  reduced. 

In  the  case  of  the  second  spot  an  opposite  direction  of  motion  is  indicated  by  polarization  observations, 
and  we  should  accordingly  expect,  for  a  point  north  of  this  spot,  motion  away  from  the  observer.  This  is 
opposed  to  what  is  found.  It  is  doubtful,  however,  whether  this  lack  of  agreement  is  more  than  apparent. 
The  slit  setting  in  this  case  was  6°  away  from  the  spot,  and  considerably  east  of  it  as  well.  It  also  fell 
on  a  greatly  disturbed  region  between  the  two  spots,  where  it  is  by  no  means  certain  that  any  well-defined 
direction  of  motion  would  predominate.  In  any  case  it  is  clear  that  a  large  amount  of  observational  ma- 
terial would  be  necessary  to  settle  the  question  of  vortical  motion  about  spots  by  means  of  spectroscopic 
observations  of  the  reversing  layer,  since  the  quantities  involved  are  considerably  smaller  than  would  be 
expected,  provided  any  definite  motion  of  this  sort,  in  which  the  reversing  layer  shares,  actually  exists. 

The  important  fact  as  bearing  on  observations  of  the  rotation  of  the  sun  is  that  large  areas  on  the  solar 
surface  may  be  affected  with  proper  motions  of  such  size  as  to  introduce  very  serious  errors  into  the  results 
when  the  areas  happen  to  fall  near  the  sun's  limb.  It  seems  very  probable  that  the  regions  of  greatest 
disturbance,  where  the  proper  motions  would  be  largest,  are  associated  with  spots ;  but  observations  with 
the  spectroheliograph  have  shown  that  such  disturbances  may  also  exist  where  there  are  no  spots.  Fur- 
thermore, an  investigation  by  myself  of  the  small  pressure  displacements  at  the  sun's  limb  has  led  to  the 
conclusion  that  regions  are  sometimes  found  near  the  center  of  the  sun  in  which  there  are  ascending  currents 
in  the  reversing  layer,  showing  motions  of  as  much  as  0.2  km.  It  is  very  probable  that  these  regions  may 
have  a  lateral  drift  as  well,  in  which  case  they  would  affect  seriously  observations  of  the  rotation  of  the  sun. 

The  possible  bearing  of  these  results  on  the  two  series  of  observations  for  1906-1907  and  1908  has  already 
been  noted.  Although  we  should  expect  differences  arising  from  this  cause  to  be  greatest  in  the  zones  of 
spot  activity,  yet  the  existence  of  a  few  cases  of  proper  motion  in  the  higher  latitudes  might  well  affect  the 
rotational  values  materially,  since  the  observations  are  not  sufficiently  numerous  to  eliminate  their  effect. 

A  similar  cause  may  perhaps  account  in  part  for  the  difference  found  by  Halm  between  the  two  series  of 
observations,  1901-1902  and  1903.  In  such  a  case  the  differences  would  represent  rather  the  excess  of  the 


126      AN  INVESTIGATION   OF   THE   ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 


effect  of  systematic  proper  motions  in  one  series  over  that  for  the  other  than  any  real  variation  in  the  sun's 
rate  of  rotation.  The  year  1903  was  characterized  by  much  greater  spot  activity  than  were  the  two  pre- 
ceding years.  Accordingly,  it  might  well  happen  that  if  the  spots  were  accompanied  by  large  areas  of 
disturbance,  and  the  points  observed  did  not  chance  to  be  symmetrically  distributed  about  them,  the  aver- 
age results  might  be  affected  by  systematic  differences.  The  whole  question  is  doubtful,  however,  and  the 
main  inference  to  be  drawn  is  that  in  taking  observations  to  determine  the  rotation  of  the  sun,  regions  as 
free  as  possible  from  disturbances  should  be  selected  and  as  large  a  number  of  observations  as  possible  be 
made,  in  order  to  reduce  the  effect  of  systematic  proper  motions. 

17.    DETERMINATION  OF  THE  SOLAR  ROTATION  WITH  THE  a  LINE  OF  HYDROGEN. 

The  details  of  the  observations  on  the  a  line  of  hydrogen  at  the  sun's  limb  and  at  points  averaging  3  mm 
inside  the  limb  have  been  given  in  Tables  15-18  in  Part  I  of  this  discussion.  If  we  collect  the  values  and 
form  normal  places  of  latitude  for  the  two  series,  we  obtain  Table  34. 

TABLE  34. — -MEAN  RESULTS  FOR  THE  o  LINE  OF  HYDROGEN. 


AT  LIMB. 

3  MM  INSIDE  LIMB. 

<t> 

»  +  », 

{ 

PERIOD. 

0 

»  +  », 

J 

PERIOD. 

° 

km 

» 

days 

0 

km 

o 

days 

o-S 

2.14 

15-2 

23-7 

0.4 

2.  II 

15-0 

24.0 

14.6 

2.03 

14.9 

24.2 

14.6 

2.OO 

14.7 

24-S 

2Q-5 

I.78 

I4.S 

24.8 

29.8 

i-73 

14.1 

25-5 

44.6 

1.41 

14.0 

25-7 

45-o 

1.38 

13.8 

26.1 

59-9 

o-9S 

13-5 

26.7 

60.3 

0.90 

13.0 

27.7 

7S-o 

0.52 

14.2 

254 

75-5 

0.47 

13-3 

27.1 

A  comparison  of  the  results  in  Table  34  shows  that  the  rate  of  change  of  the  motion  is  very  rapid  inward 
from  the  limb,  and  that  the  points  nearer  the  edge  give  not  only  larger  absolute  values,  but  also  less  change 
of  velocity  with  change  of  latitude.  An  effect  of  this  sort  would  seem  very  probable  from  the  consideration 
that  the  level  of  effective  absorption  for  points  near  the  limb  in  the  case  of  an  element  like  hydrogen  is 
probably  decidedly  higher  than  that  for  points  inside  the  limb.  Direct  evidence  of  this,  although  not  of 
very  high  weight,  was  furnished  by  the  results  obtained  from  some  plates  taken  so  close  to  the  limb  that 
upon  two  of  them  the  bright  chromospheric  line  was  shown.  These  plates  gave  very  large  values  through- 
out, and  essentially  no  evidence  of  change  of  angular  velocity  with  latitude. 

TABLE  35.  —  COMPARISON  OF  RESULTS  FOR  o  LINE  OF  HYDROGEN  WITH  THOSE  FOR  REVERSING  LAYER. 


Ha.  AT  LIMB. 

Ha  3  MM  INSIDE  LIMB. 

REVERSING  LAYER. 

0 

r  +  », 

J 

PERIOD. 

f-t-tij 

1 

PERIOD. 

v  +  vl 

t 

PERIOD. 

0 

km 

o 

days 

km 

o 

days 

km 

o 

days 

0.5 

2.14 

15-2 

23-7 

2.  II 

15-0 

24.0 

2.06 

14.6 

24.6 

14.6 

2.03 

14.9 

24.2 

2.00 

14.7 

24-S       . 

I-9S 

14.3 

2S.2 

29-5 

I.78 

14-5 

24.8 

i-73 

14.1 

25-5 

1.67 

13-7 

26.4 

44.6 

I.4I 

14.0 

25-7 

1-39 

13.8 

26.0 

1.29 

12.9 

27.9 

59-9 

o-9S 

13-5 

26.7 

0.92 

13-0 

27.8 

0.81 

ii-S 

31-3 

75-° 

0.52 

14.2 

25-4 

0.48 

13-3 

27.1 

0.40 

10.9 

33-1 

In  order  to  compare  the  results  of  the  two  series  on  the  a  line  of  hydrogen  with  each  other  and  with 
those  given  by  the  reversing  layer,  the  values  in  Table  34  are  reduced  to  the  same  latitude  and  collected 
in  Table  35  along  with  the  reversing  layer  results.  The  latter  are  from  the  1908  observations. 


ROTATION   DERIVED    FROM    X   4227    OF   CALCIUM. 


127 


An  inspection  of  the  results  in  Table  35  leads  to  two  important  conclusions.  First,  that  the  absolute 
velocity  of  rotation  given  by  Ha  is  much  higher  than  that  found  for  the  reversing  layer.  Second,  that  the 
law  of  change  of  angular  velocity  with  latitude  is  quite  different,  the  velocity  being  more  nearly  uniform, 
or  the  equatorial  acceleration  less,  than  in  the  case  of  the  reversing  layer. 

As  has  been  stated  previously,  it  seems  probable  that  the  explanation  of  these  results  is  to  be  found  in 
the  comparatively  high  level  occupied  by  hydrogen  gas  in  the  sun's  atmosphere.  The  change  of  angular 
velocity  with  latitude  which,  as  we  have  seen,  appears  to  be  most  rapid  for  the  reversing  layer,  sun-spots, 
and  facuhe,  is  almost  certainly  connected  to  some  extent  with  the  effects  of  internal  friction.  This  fric- 
tion no  doubt  decreases  outward  from  the  photosphere,  with  the  result  that  for  the  higher  gases  the  ten- 
dency is  toward  a  more  nearly  uniform  rate  of  rotation  in  all  latitudes.  Similarly,  as  the  effect  of  friction 
is  reduced,  the  higher  gases  tend  to  acquire  greater  velocities,  the  tendency  toward  orbital  motion  gradually 
becoming  stronger.  It  would  of  course  be  necessary  to  go  to  immense  distances  from  the  sun,  certainly 
beyond  the  corona,  before  the  motion  could  in  any  sense  be  considered  truly  orbital,  but  a  tendency  in  this 
direction  might  well  begin  at  a  comparatively  low  level.  It  is  of  interest  to  note  in  this  connection  that 
Campbell's  result  for  the  rotation  of  the  corona  indicates  a  very  short  period.  Thus  Campbell  writes  (22) : 

The  difference  of  the  determinations  for  the  E.  and  W.  sides  is  o.i  i  t.m.  (Angstrom),  corresponding  to  a  relative  velocity 
in  the  line  of  sight  for  the  two  sides  of  6.2  km,  and  a  rotational  velocity  of  3.1  km  per  second.  However,  I  regard  this  last 
result  as  subject  to  a  possible  error  of  at  least  ±  2  km  per  second,  partly  on  account  of  unavoidable  errors  of  observation,  but 
principally  on  account  of  the  character  of  the  bright  line. 

A  linear  rotational  velocity  of  3.2  km  corresponds  to  a  daily  angular  motion  of  about  22??, or  to  a  period 
of  rotation  of  15.9  days.  It  seems  probable  from  the  Ha  results  that  at  the  level  of  even  the  lowest  parts  of 
the  corona  very  little  equatorial  acceleration  would  be  found. 

The  marked  difference  in  the  behavior  of  Ha  at  the  sun's  limb  as  compared  with  the  violet  lines  of 
the  hydrogen  series  makes  it  probable  that  a  difference  in  the  level  of  effective  absorption  is  involved. 
Accordingly,  I  have  made  a  few  attempts  to  measure  the  rotational  velocity  given  by  the  Hy  line. 
The  results  appear  to  indicate  that  Hj  gives  values  averaging  about  0.05  km  less  than  Ha,  but  they  are 
of  extremely  low  weight  on  account  of  the  difficulty  of  measurement  of  this  line.  The  recent  studies  by 
Hale  and  Ellerman  of  the  hydrogen  flocculi  photographed  with  the  different  lines  of  the  hydrogen  series 
would  indicate  that  some  such  effect  might  be  expected  (23). 

18.    DETERMINATION  OF  THE  SOLAR  ROTATION  WITH  X  4227  OF  CALCIUM. 

The  details  of  the  observations  on  the  line  X  4227  of  calcium  and  summaries  of  the  results  are  given  in 
Tables  19  and  20  of  Part  I.  If  we  combine  the  values  about  normal  points  of  latitude,  we  obtain  the  results 
found  in  Table  36.  The  reversing  layer  values  from  the  observations  of  1908  are  added  for  comparison. 

TABLE  36.  —  COMPARISON  OF  RESULTS  FOR  \422^  OF  CALCIUM  WITH  THOSE  FOR  REVERSING  LAYER. 


X4227 

REVERSING  LAYER. 

0 

ti  +  Jij 

t 

PERIOD. 

»  +  », 

I 

PERIOD. 

• 

km 

o 

days 

km 

o 

days 

°-4 

2.12 

15-1 

23.8 

2.06 

14.6 

24.6 

IS-O 

2.O2 

14.8 

24-3 

1.94 

14-3 

2S-2 

29.9 

1-75 

14.3 

25.2 

1.67 

13.6 

26.4 

44-9 

1.36 

13.6 

26.5 

1.29 

12.9 

28.0 

60.0 

0.88 

12-5 

28.8 

0.81 

"-S 

31-3 

74-8 

0.49 

13-3 

27.1 

0.40 

10.9 

33-0 

These  results  indicate  that  the  calcium  gas  producing  X  4227,  like  hydrogen,  moves  more  rapidly  than 
the  reversing  layer,  and  shows  less  change  of  velocity  with  increasing  latitude.     The  differences  are  less, 


128     AN  INVESTIGATION   OF  THE   ROTATION  PERIOD   OF  THE   SUN  BY  SPECTROSCOPIC  METHODS. 

however,  than  for  hydrogen  near  the  limb,  and  approximately  equal  to  those  for  hydrogen  taken  at  a  dis- 
tance of  3  mm  inside  the  limb. 

An  investigation  of  two  calcium  lines  in  the  less  refrangible  part  of  the  spectrum  has  been  made  by  Perot 
with  interference  apparatus  (17).     Preliminary  values  of  the  angular  velocity  given  by  him  are  as  follows : 


X 

0=0° 

<t>  =  45-7 

5349-6 
6122.4 

15-1 
14-7 

14.2 
14.2 

Mean 

14.9 

14.2 

At  the  equator  these  results  are  identical  with  those  obtained  here  for  X  4227,  but  at  45°  they  are  con- 
siderably larger.  They  may,  of  course,  be  modified  considerably  by  more  complete  results,  but  it  seems 
doubtful  whether  the  entire  difference  will  disappear.  If  it  persists,  it  would  seem  to  indicate  a  higher  aver- 
age level  for  these  lines  than  for  X  4227.  The  broad  wings  of  the  latter  line  point  to  a  region  of  consider- 
able density  and  consequently  of  low  level  for  their  origin,  but  there  can  be  but  little  doubt  that  the  central 
portion  of  the  line  rises  to  a  considerable  altitude.  Moreover,  the  size  of  pressure  displacements  found  for 
the  two  less  refrangible  lines  at  the  sun's  limb  would  appear  to  argue  against  a  very  high  level  origin  (24). 
All  three  of  the  lines  are  found  in  the  spectrum  of  the  chromosphere. 


VtV, 

Km 
7.20 

2.00 
1.80 

^^^SSs^, 

^5S-». 

Uniform  angular 
Ha  at  limb 

velocity  

""""-C^T"'-^ 

l§5^> 

\  42Z7 
Reversing  layer       —  —  

1.60 

o^^s. 

1.40 

^xj^ 

^x 

1.20 

x^> 

\xx 

1.00 

^ 

0.80 

\^ 

0.60 

^:^% 

\ 

0.40 

^ 

N^ 

0.20 

X^ 

Sk 

VfV, 
0.00 

"V 

0               9                  ID"                                 ZO-                                 30'                                 40-                                  50° 

i-                         -, 

—  •  «•  80* 

FIG.  4.  —  Variation  of  radial  velocity  with  heliographic  latitude  for  the  different  lines  observed.  The  curve  for  the  reversing  layer  is 
fronUhe  mean  results  for  the  two  series  of  observations.  The  radial  velocity  curve  of  a  body  rotating  uniformly  with  a  motion 
of  15^0  a  day  is  added  for  comparison. 


COMPARISON   OF   RESULTS. 


129 


19.    COMPARISON  OF  RESULTS  FROM  ALL  THE  LINES  INVESTIGATED. 

A  remarkable  feature  of  the  results  for  ^  4227  and  the  two  series  on  the  a  line  of  hydrogen  is  the  sudden 
increase  in  angular  velocity  between  60°  and  75°  of  latitude.  Too  much  stress  should  perhaps  not  be  laid 
upon  this,  since  in  high  latitudes  the  angular  velocity  is  extremely  sensitive  to  small  differences  in  linear 
velocity ;  and  with  lines  as  difficult  of  measurement  as  these  the  entire  effect  could  readily  be  laid  to  this 
source.  A  change  of  0.018  km  at  75°,  for  example,  would  reduce  a  value  of  f  of  i4?o  to  i3?S-  A  similar 
effect,  however,  was  found  for  the  lines  of  lowest  level  in  the  reversing  layer,  the  lines  of  lanthanum  and 
cyanogen  giving  exceptionally  large  deviations  in  the  higher  latitudes  and  in  directions  opposite  to  those 
found  for  these  high-level  lines.  Accordingly,  there  seems  to  be  a  slight  presumption  in  favor  of  the 
existence  of  some  cause  toward  the  pole  of  the  sun  which  tends  to  make  the  deviations  from  the  mean 
exceptionally  large  for  such  lines  as  give  abnormal  values. 

The  results  for  the  two  series  of  observations  on  Ha,  for  \  4227,  and  for  the  reversing  layer  are  shown 
graphically  in  Fig.  4.  The  fifth  curve,  indicated  by  a  dotted  line,  represents  the  curve  of  linear  velocity  of 
a  body  rotating  with  the  uniform  angular  velocity  of  i5?o  a  day.  It  is,  of  course,  the  ordinary  cosine  curve. 

In  conclusion,  it  will  be  of  interest  to  give  a  graphical  representation  of  the  results  found  in  this  inves- 
tigation for  all  the  lines  studied.  Accordingly,  I  have  collected  the  formulas  which  represent  the  solution 
by  least  squares  of  the  values  of  the  angular  velocity  obtained  for  the  reversing  layer,  Ha,  and  \4227,  and 


14.5 


14.0 


13.5 


13.0 


IZ.5 


11.5 


V 


Ha  at  limb 
Her  within  limb 
A,  4227 

Reversing  layer 


\ 


80° 


90* 


"   0°      <t>          10°  20°  30°  40°  50°  60°  70° 

FIG.  5.  —  Curves  representing  the  values  of  the  angular  velocity  given  by  the  empirical  formula: 
derived  from  the  observations  of  Ha.,  \  4227,  and  the  reversing  layer.  For  the  last  named  the 
mean  of  the  two  series  of  observations  is  used. 


130     AN  INVESTIGATION  OF   THE  ROTATION  PERIOD   OF   THE   SUN  BY   SPECTROSCOPIC   METHODS. 


have  plotted  the  results  for  latitudes  o°  to  75°  in  Fig.  5.     The  formula  obtained  from  the  mean  results 
for  the  two  series  of  observations  has  been  employed  for  the  reversing  layer. 

Reversing  layer   ......  £=  11.04  +  3-5°  cos2  $ 

X  4227    .........  £  =  12.5    +2.4    cos2<£ 

Ha  (within  limb)      .....  f  =  12.8    +2.0    cos2<£ 

Ha  (limb)  ........  £=13-6    +1.4    cos2^) 

The  numerical  values  of  the  angular  velocity  resulting  from  these  equations  are  shown  in  Table  37  for 
every  15°  of  latitude.  The  values  given  for  the  pole  are  extrapolations  based  on  the  formulae,  and  are,  of 
course,  subject  to  great  uncertainty.  An  investigation  of  the  region  between  latitude  75°  and  the  pole 
undertaken  with  powerful  apparatus  would  prove  of  great  value  in  deciding  many  questions  connected 
with  the  law  of  the  sun's  rotation. 

TABLE  37.  —  FINAL  RESULTS  FOR  THE  ANGULAR  VELOCITY. 


<t> 

REVERSING 
LAYER 

X  4227 

Ha 

(INSIDE  LIMB) 

Ha. 

(LIMB) 

o 

14-54 

14.9 

14.8 

15.0 

IS 

I4-3I 

14.8 

14.7 

14.9 

3° 

13-67 

14-3 

14-3 

14.6 

45 

12.79 

13-7 

13-8 

14-3 

60 

11.92 

13-1 

13-3 

13-9 

75 

11.27 

12.7 

13.0 

13-7 

Pole 

(11.04) 

(12.5) 

(12.8) 

(13.6) 

20.    GENERAL  SUMMARY. 

The  principal  results  of  this  investigation  may  be  summarized  as  follows  : 

1.  Two  series  of  observations  of  the  rotation  of  the  sun  made  during  1906-1907  and  1908  give  results 
agreeing  closely  with  one  another  in  latitudes  o°  to  50°.     Above  50°  the  1908  observations  give  smaller 
values,  the  greatest  difference  being  at  70°  and  amounting  to  about  0.039  km. 

2.  These  differences  are  probably  to  be  ascribed  to  small  systematic  errors  in  the  earlier  series  of 
observations  arising  from  the  character  of  the  solar  image.     They  may  possibly  be  ascribed  in  part  to 
proper  motions  in  the  sun's  reversing  layer. 

3.  The  evidence  from  these  results  is  opposed  to  the  existence  of  a  variation  in  the  sun's  rate  of  rotation, 
unless  the  variation  be  of  long  period.     Not  only  is  there  no  appreciable  difference  between  the  two  series 
of  observations  in  the  lower  latitudes  and  the  regions  of  greatest  spot  activity,  but  the  agreement  of  the 
1908  results  with  the  values  of  Duner  make  a  variation  during  the  interval  very  improbable. 

4.  Both  series  of  observations  agree  in  showing  that  the  lines  of  different  elements  give  different  values 
of  the  rotational  velocity.     Lines  of  lanthanum  and  cyanogen  give  low  velocities.     These  elements  are 
known  to  lie  at  low  levels  in  the  solar  atmosphere.     Certain  lines  of  manganese  and  iron  give  high  velocities. 

5.  Lines  which  give  systematically  large  or  small  values  of  the  velocity  appear  to  give  the  largest  devia- 
tions from  the  mean  in  high  latitudes. 

6.  The  1908  observations  are  satisfactorily  represented  by  an  empirical  formula  of  the  Faye  type. 
The  1906-1907  observations  show  a  tendency  to  systematic  residuals  with  an  equation  of  this  form,  and 
require  the  addition  of  another  term  for  adequate  representation.     The  combined  results  for  the  two 
series  are  very  closely  represented  by  the  formula 


SUMMARY   OF   RESULTS.  131 

7.  The  fact  that  these  observations,  as  well  as  those  of  Duner  and  Halm,  are  satisfied  by  the  Faye 
equation  indicates  that  this  represents  with  a  considerable  degree  of  accuracy  the  law  of  the  sun's  rotation 
to  within  10°  of  the  pole. 

8.  A  comparison  of  the  probable  errors  of  the  1906-1907  observations  with  those  of  the  1908  series 
indicates  a  marked  gain  in  accuracy  for  the  latter.     The  results  for  both  series  appear  to  show  a  decided 
superiority  for  the  photographic  method  over  the  visual  so  far  as  the  degree  of  accuracy  is  concerned. 

9.  The  displacements  of  the  spectrum  lines  may  be  influenced  seriously  by  proper  motions  of  the  re- 
versing layer.     These  may  be  very  large  in  the  neighborhood  of  the  disturbed  regions  which  are  usually 
associated  with  sun-spots.     A  value  amounting  to  0.2  km  has  been  observed  in  one  such  case.     It  is  most 
important  that  in  observations  of  the  rotation  of  the  sun  such  regions  should  be  avoided  so  far  as  possible. 

10.  A  study  of  the  a  line  of  hydrogen  shows  that  the  gas  producing  this  line  movesat  a  muchmore  rapid 
rate  than  the  general  reversing  layer,  and  that  the  change  of  angular  velocity  with  increasing  latitude  is 
very  much  less.    At  the  equator  the  difference  from  the  reversing  layer  is  about  o°5,  while  at  75°  of  lati- 
tude it  amounts  to  over  2.5. 

1 1 .  The  results  for  the  angular  velocity  obtained  from  Ha  at  a  short  distance  inside  the  limb  are  appre- 
ciably smaller  than  those  for  the  line  at  the  limb.     This  is  probably  due  to  the  lower  average  level  of  the 
gas  involved  in  the  formation  of  the  line  within  the  limb. 

12.  The  line  X  4227  also  gives  decidedly  larger  values  of  the  rotational  velocity  than  do  the  lines  of  the 
reversing  layer.     The  values  are,  however,  smaller  than  for  Ha  at  the  sun's  limb,  and  not  far  from  equal  to 
those  for  Ha  within  the  limb.    The  equatorial  acceleration  is  considerably  greater  for  X  4227  than  for  Ha 
at  the  limb. 

13.  The  observations  on  both  Ha  and  X  4227  appear  to  indicate  an  increase  in  the  angular  velocity  near 
the  sun's  pole.     This  is  the  converse  of  the  result  found  for  the  lines  of  the  reversing  layer  which  give 
abnormally  low  values,  and  may  perhaps  be  a  genuine  effect. 

14.  The  comparison  of  the  results  on  Ha,  X  4227,  and  the  lines  of  the  reversing  layer  shows  that  the 
observations  are  all  satisfied  by  a  law  of  rotation  in  which  the  velocity  increases  and  the  equatorial  accelera- 
tion decreases  with  increasing  distance  outward  from  the  sun's  surface.     The  cause  of  this  probably  lies 
in  the  effects  of  friction  in  the  lower  portions  of  the  solar  atmosphere. 

15.  Comparison  with  the  results  for  sun-spots,  faculae,  and  the  calcium  flocculi  gives  the  following 
sequence  in  order  of  decreasing  equatorial  acceleration  :  spots  and  faculas,  X  4227,  calcium  flocculi,  Ha. 
The  reversing  layer,  however,  shows  a  greater  amount  of  equatorial  acceleration  than  any  of  these.     If  we 
assume,  in  accordance  with  Wilsing's  theory,  that  there  are  two  surfaces  of  constant  angular  velocity  in  the 
case  of  a  rotating  body  such  as  the  sun,  it  is  possible  that  the  reversing  layer  may  lie  in  the  position  where 
the  departure  from  this  condition  is  a  maximum.     On  this  basis  the  spots  and  faculae  which  lie  near  the 
inner  surface  of  uniform  velocity,  and  X  4227,  the  calcium  flocculi,  and  Ha,  which  lie  nearer  the  outer 
surface,  would  all  show  less  equatorial  acceleration. 

I  am  under  the  greatest  obligation  to  Mr.  Hale  for  many  suggestions  during  the  progress  of  this  inves- 
tigation and  for  a  deep  interest  in  it.  Among  the  numerous  advances  in  solar  spectroscopy  made  possible 
by  his  design  and  construction  of  the  tower  telescope  is  to  be  included  the  marked  gain  in  accuracy  of  the 
later  series  of  observations  of  the  rotation  of  the  sun.  I  am  also  greatly  indebted  to  Miss  Lasby  and  to 
Miss  Waterman,  of  the  Computing  Division,  for  aid  in  the  measurement  and  reduction  of  the  plates. 
The  measurement  of  many  of  the  plates  has  been  carried  out  by  Miss  Lasby  alone,  and  a  large  part 
of  the  great  labor  involved  in  their  reduction  and  in  the  solution  of  the  empirical  formulae  has  been  divided 
between  Miss  Lasby  and  Miss  Waterman. 


132 


BIBLIOGRAPHICAL   REFERENCES. 


BIBLIOGRAPHICAL  REFERENCES. 


1.  VOGEL,  " Spectralanalytische  Untersuchungen  an  der  Sonne," 

Astronomische  Nachrichten,  78,  248,  1872. 

2.  YOUNG,  "Observations  on  the  Displacements  of  Lines  in  the 

Solar  Spectrum  caused  by  the  Sun's  Rotation,"  American 
Journal  of  Science,  Third  Series,  12,  321,  1876. 

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and  Other  Data  resulting  from  an  Attempt  to  determine 
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23.  HALE  AND  ELLERMAN,  "On  the  Nature  of  the  Hydrogen  Floc- 

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